Yes, you have to trust the app developer. And Apple is acting as a check/oversight on that relationship, too. Whether it's of use or not, that is really another discussion.

That is my personal red line also. But I am 100% in support of them enforcing signed apps for the majority, but it should be something you can turn off for advanced users via firmware/bios. My mom does not need to run unsigned apps she finds on the Internet.