The typical reason is that there's a whole host of systems that might be sending e-mail on behalf of the company, so there might be some delay (generally far less than 30 days) for it to flow through whatever integrations are set up, and hey - since there's going to be a delay anyway, why potentially shoot yourself in the foot by giving yourself less than what you're entitled to by law?
That's possible. But if DNS changes can propagate throughout the entire world in 24 hours, seems like removing my email from a bunch of Internet databases could too.
I'm assuming that the thought process businesses are going through goes something like:
- We have a complex series of integrations (marketing automation -> CRM system -> app -> transactional e-mail provider) (as one example) where propagation isn't real time and could take a few days (if say, each of these were propagated on a nightly batch).
- Something could go wrong with any of these.
- It's better to err on the side of caution and give a super-conservative estimate and always beat it by a huge margin, than give an accurate estimate and occasionally break it (particularly with something as sensitive as unsubscribes).
