Well there is stuff being done here - you can read here: Webflow, your EU customers need a statement (Privacy Shield) - #26 by Dennis_K
So we’re (hopefully) not the unwanted child(s).
My guess is that it’s just very very complicated matter, which involves tons of legal stuff, but also how to get this technically right.
Also it’s all still fairly new, especially for US-based businesses, so i think investigating each/every system that (in this case) Webflow uses, and in order to get the “GDPR-PROOF” Label on each and everyone which could involve all kinds of technical and/or legal changes, is a major(!) undertaking. This could very well take many months, if not, years to do well.