I disagree with the analogy. Trying to use the same analogy: If I were a one person entrepreneur trying an MVP, I would be building a bicycle, not a car. And what I suggest is have the right to put a sticker on the bicycle: "Warning, this is not compliant with the car regulations" to make sure people don't have false expectations. (Because I agree that in the real world, only a fool wouldn't be able to differentiate between a car and a bicycle, but for web services, this isn't an easy task)

A one person entrepreneur might not consider him/herself to be "being in the webservice business". Instead he/she would consider being in the business of [whatever problem the MVP is trying to solve]. It just hapens that in the 21st century, most of innovation happens online.

Back to your car analogy, it seems that people on one side argue that all companies "being in the webservice business" are 'car makers'. some people on the other side of the argument might say it's not.

Also, ultimately, it's possible that after spending a lot of time and hours examining the legal requirements of GDPR, a startup realizes it's not technically hard to comply, but the issue here isn't implementing the requirements, it's more about getting all the legal analysis, certification, handling customers requests, etc.

> If you disagree, should the US also stop prosecuting VW for the diesel cheating?

In that case, VW has clearly been in the car business for much more than 2 years, and in my example "X users", a good value for X would be something order of magnitudes less than the number of VW customers around the globe. So no, the US would continue prosecuting VW.