lol, they'd be out the door so fast for abusing the rest of the group's sensitivity that way at my table.
Given that the offender was also the host... we did walk.
They don't build trust for me; in fact, the opposite.
As a player if I see an X-card or similar my first thought is that now I a) have to wonder just where the GM is planning to take this game and b) have to now trust the other players (or even the GM!) not to use i; 'cause I know I sure as hell won't be using it.
I feel much the same way. Then again, I don't like running games where the rules encourage the kinds of themes that an X-Card is a reasonable precaution for.
if someone asks you to put a seatbelt on, do you wonder exactly how fast they are going to drive, and then worry about trusting the other passengers not to use it to leave you trapped in the car?
If they're driving a golf cart, public transit bus, or an indoor transport (such as at Chigaco's O'Hare airport (ORD)), hell yes I wonder
If it's a standard road car, no. But that is where your metaphor fails.
See, with RPGs, the issue of safety shouldn't require an X-card in mainstream RPGs. But a huge number of low-fanbase RPGs are filled with various "edgy" and/or offensive and/or narrowly targeted audiences. In those, the X-card or an equivalent is useful. But I generally don't want to play games where it's going to even come close to useful with people I don't trust to be useful.
I've had three players abuse fade to black options in the last 10 years. In all three cases, munchkins prone to rules-lawyering. In two of the cases, it wasn't the only toxic behavior. In the third, it was explicitly to prevent an encounter that the player knew was going to benefit others but not his character. 2 of the three were in public space games.
If you've never had someone abuse it, consider yourself lucky. Hell, if it had beena thing in the 80's, I'd have used it to avoid certain boring-to-me-but-not-to-others scenes as a player.