The only solution is to be rock-solid in refusing to do anything if there isn't a ticket for it. Your nine-thousand-percent-consistent reply to those emails, text messages, and voice calls needs to be "Yeah, make a ticket about it. I've shown you how, and that's the way we do it. No ticket, no action from me."
If you can't be that "mean" about it, you'll have to be a make-my-own-tickets doormat forever. In that perspective, doesn't feel all that "mean" any more, does it?
Perhaps I've been spoiled having worked almost exclusively in organizations where it's completely acceptable to get a message on Slack, or Teams, or email, or whatever, with some bug or issue, and respond with "please create a ticket" and the person... creates a ticket.
Yeah if nobody uses the system, or if you have to expend organizational capital to get them to do it (they view it as doing something for you instead of just doing their job), the system will by definitely be worth less and be less helpful.