Why football clubs from israel kazakhstan compete in euro cups?

Answer 1

Politics, essentially.

Israel is in a funny position. A number of it's neighbours don't recognise the state of Israel, so there'd be issues with accepting an Israeli team into their countries. Moreover, given the history of that region, it could easily inflame already feisty tempers should an Israeli team go to, say, Iran.

Kazakhstan see themselves as having more in common with Europe than Asia. As a nation, they aim to be more western and their participation in European competitions helps with that.

It's not just those two. Australia now play in the Asian confederation as they'd outgrown the Oceania competition and the Australian FA felt they were stagnating. If they were to progress as a football nation, then they had to get a better level of competition. Beating American Samoa 31-0 doesn't help either side progress.