Usage of *Could have* Fact vs Possibility?

Question

I read this sentence in a Youtube video that explains the meaning of even if.

She could have paid more, but she'd got the same service.

with even if:

Even if she had paid more, she'd have got the same service.

It appears from the example that "could have" indicates a real event that actually took place in the past - not merely a possibility. (the woman had actually paid more).

Yet it is very confusing when "could have" indicates a possibility like in

"You could have completed it sooner."

So how could we know the real meaning of "could have" in both cases ? For Example:

Simon could have told her.

Did Simon tell her or not ?

Source: Youtube video Minute 9:50

Thank you

Answer 1

She could have paid more, but she'd got the same service.

In this sentence, "could have paid" indicates that she had that possibility in the past but did not use that possibility.

You are right, could have + verb is an ambiguous construction, and we rely on context to derive its true meaning.

From the Macmillan Dictionary:

1. used for saying that something was possible in the past, even though it did not happen
   You could have been killed.
   I could have told you, but I didn’t think you would listen.
   She could have married Gerald if she’d wanted to.

2. used for saying that perhaps something was true, although you do not really know
   The explosion could have been caused by a gas leak.
   It could have been Dan, but I’m not sure.

---

Related:

• Another question discussing the ambiguity of 'could have'