You could have just said "no, I don't have any evidence that the Texas Theater tore tickets" rather than just trying to shift the burden of proof.
Other than Butch Burroughs telling the Commission that part of his job was "taking tickets," you are technically correct that there is no direct evidence for the idea. In the sense of "technically correct" that makes other people roll their eyes comment as to how you're acting like a total dorkotronic unit.
For that matter:
I also have no direct evidence that the DISD was taking attendance that day.
I also have no direct evidence that other people eat breakfast when I'm not around.
I also have no direct evidence that the alleged nation of Uzbekistan exists.
I also have no direct evidence that the Moon orbits the Earth.
I also have no direct evidence that you're a human being, rather than some poorly-rigged software failure, programmed by drunken wombats, aimed at passing a C-league junior-varsity Turing test.
That being said:
Taking tickets, tearing them, then giving a punter the stub as a proof of purchase is a ubiquitous activity at theaters. That's because there are well-established practical reasons behind doing it that way: it's a cheap way to cancel the ticket (so it can't be re-used by someone else) while leaving the customer a receipt proving that they are entitled to to whatever acccess/services granted by the ticket. Ubiquitous enough that it's reasonable to assume that the Texas Theatre did --especially if Burroughs was "taking tickets."
