Volkswagen-sized companies would be subject to the 4% of revenue limit, since that's >20M EUR. That 4% seems high to me, but not insane.
The 20M seems insane to me. If the standard for smaller companies were e.g. 100% of the last five years of revenue plus 50k EUR, then can you imagine a case where it would be cheaper to violate the law and keep paying the fine? That would be a lot less menacing to small, non-commercial or semi-commercial projects.