Yep, that might be true for certain industries.

But logs don't count as the transactional data that needs to be kept for legal reasons.

That depends entirely on what they're logging and why.

There are always time limits that apply, which means you need to have a process to delete the relevant log entries (or the whole log) eventually.

Sure, like 7 years. https://business.gov.nl/regulation/keeping-business-records/