Looks like you had quite an experience. I'm also not a vegan, nor vegetarian. I eat almost all I want, selecting of course the healthiest options. However, vegan dishes are fine from time to time.

What I don't like in a restaurant is when as you said, your burger is falling apart, you make a mess and/or you get out dirty, not to mention the price of the meal.
I'd say if the price is high or higher than usually, the meal must be exceptional.

The cappuccino story made me smile. I've been a coffee addict for decades, gave up drinking coffee one hand a half year ago. However I've hardly had cappuccino or coffee with cream as I liked my coffee black. Not that is makes you feel better, but I would have made the same mistake myself :)

My question is, would you have vegan meals/burgers in the future, after this experience? 🙂