When there is "legitimate purpose" there isn't reason to as soon items are put in the shopping cart this has to be tracked (be it session in url, cookie, local storage, ...) and no consent is needed.

The exact definition of "legitimate purpose" is unspecific (which is important to be able to adapt to development of new services) which leads to some lawyers being careful.

I also claim that some lobby groups promote having too many and too big consent banners to move blame from tracking companies to the EU ("stupid EU forcing all those banners!") in order to reverse the policy on tracking, which seems to have some effect.