For the OP,
Kids that just turn “vegan” don’t usually suddenly throw out the shoes they already have. It takes a while for a big change like that to filter into all parts of your life.
Having said that, if they are giving you a hard time and still wearing leather, feel free to call out that hypocrisy. I think doing less harm is the way to go, and sometimes at the beginning when you realize how fucked up the regular way of doing things realky is, you want everyone to know, and thats where the crusading attitude comes from.
But like everything at the beginning, people usually suck at it, and they need to refine their approach. So yeah, call these kids out, it helps them learn too.
Now for the leather/synthetic debate.
Leather is pumped full of chemicals to prevent biodegrading as well, and is not really any greener than synthetic is seems. From that standpoint, canvas is probably the best, even if it wears the worst.
It’s about time someone retried the rubber grip tape idea