Titles, especially in journalism, aim to immediately draw in readers.
Journalists have to be quick and efficient.
Instead of saying "Trump plans to meet with the game industry in order to discuss gun violence next week," journalists try to stick to a condensed version of the sentence, one that still makes sense and gets the point across.
From a grammatical point of view, please consider this definition provided by Google:
["to" may be used] in various phrases indicating how something is related to something else (often followed by a noun without a determiner).
"made to order"
Compared to other languages, such as French, English is rather lenient in many respects. As you can see above, this is a similar situation to the Trump example.
The best reasoning for this is the attention-grabbing nature of journalism.