Most services I've seen set tracking to the maximum by default, then present the user with an "OK, accept everything" and a less obvious "more options", where they must disable numerous default-on tracking options. That's opt-out, not opt-in, hardly simple or concise.

There are also plenty which simply say: accept our tracking or you can't use the service. Which is plainly in breach of Ch. 2 Art. 7.4 of the GDPR.