"I never asked that question before."
"I never said that."
From my memories I forgot where I heard this. English speakers especially Americans sometimes use simple past to mean present perfect, is that true?
At least for these statements, this isn't a matter of using simple past to mean present perfect.
Using simple past associates the statements with some sort of scope. For example, "I never said that" would be appropriate in the following conversation:
Alice: "I got you that sandwich."
Bob: "What are you talking about?"
Alice: "You said you wanted a sandwich."
Bob: "I never said that. That was Paul."
Bob may have, at some point in his life, said he wanted a sandwich. However, he never said it in the conversation Alice is thinking of. (Paul said it.)
In contrast, "I have never said that." would be a much stronger statement. It would mean that never, in Bob's entire life, has he ever said he wanted a sandwich.
As for "I never asked that question before," the scope is before... something. Probably before the person did ask that question. That could be recent, or it could have happened a while ago. If it's very recent, present perfect could also be appropriate. If it was 5 years ago, simple past is appropriate, but present perfect wouldn't be.
English speakers especially Americans sometimes use simple past to mean present perfect, is that true?
Indeed, many Americans don't internally make a significant psychological distinction between the simple past and the present perfect as separate tenses at all, which is why they drop the "have." It is a distinction in tenses that only some Americans would recognize (it may be a function of different regional dialects of American English). Only a minority of Americans could articulate any difference in meaning between these sentences with and without the word "have".
There is a theoretical difference which another answer to your question explains. But the distinction between the simple past and past perfect is more important than other languages that were a model for English grammar texts than it is a deeply ingrained part of vernacular American English. Only the most pedantic fluent speakers of American English would find the use of the simple past instead of the past perfect to be "jarring" or would think that it sounds seriously incorrect. At most using the simple past when the past perfect is intended would cause the person speaking that way to be perceived as speaking in a slightly less formal speech register.
Yes and No.
It's not so much that Americans use the Simple Past to mean the Present Perfect. It's that we often aren't noticing (or focusing on) the connection with the present at all. It indicates that the speaker is looking at it as an event wholly in the past with little-to-no connection to ongoing events, and so is using the Simple Past accordingly.
We probably ought to consider the Present Perfect's applicability to the situation. But that's a different matter. And you certainly won't sound strange to an American ear if you recognize it (and use Present Perfect) when speaking yourself.
I'm not a linguist but I think one thing that might be at play is that most American English speakers would prefer "I've never" to "I have never". And there's a tendency to drop sounds like the 've' in "I've". I notice this in my own speech sometimes. I will be thinking "I've", but I don't say it out loud, or it's at least so quiet that no one could be expected to hear it. Other examples of this trend are things like "I got this" or "I got it" (e.g.: in baseball.) The 'have' is implied/assumed.
No. English speakers especially Americans never use Simple Past to mean Present Perfect. Your sentences can be expressed using Past Simple or Present Perfect. The following text is from the Britannica Dictionary 1:
Use the simple past when the action started in the past, finished in the past, and is not continuing now. Use the present perfect when the action started in the past and is continuing now.
The simple past tells us that an action happened at a certain time in the past, and is not continuing anymore. It doesn't tell us anything about when an action happened, so more information needs to be given with this verb form, such as when the action took place.
The present perfect tells us that an action started in the past and it is still happening now, or it is something that happens regularly. We may need more information to tell us how long it has been going on. It may also tell us that the time period it started in is still going on.
I (have) noticed Australians and Fijians do that too. This year I'm planning to travel (to) other countries so will (get to) see what others are saying. English speakers in New Zealand, Thailand and Singapore (do) say it though. Semantically the phrase makes sense so (it) might be redundant in some communities, similar to (the word) "did" eg. Instead of "I did have it", more common now is "I had it".
Americans have their own accepted American English (though) anyway. One common phrase is "off of" eg. "I took the spoon off of the table" when "I took the spoon off the table" makes perfect sense, or "go ahead and take that spoon" instead of "take that spoon".
"have" by definition refers to possession eg. I have one nose. To explicitly state "have" in phrases where it's redundant would then be justified when emphasis is being made, which could otherwise be done by repetition. eg. "I had a Ferrari once" replaced by "I have had a Ferrari once".
The word itself requires a lot more effort (energy and air volume) to be pronounced so is fairly common to drop it, especially when it's redundant or can be replaced by a cheaper (less effort to pronounce) word eg. "Did you eat" instead of "Have you had anything to eat".