You might be missing the point. Again, the EU will send them a bill and a firm letter, but they don’t have any authority to actually demand payment. That fact has nothing to do with GDPR but with the fact that it’s an entirely different sovereignty.
The EU could sue them, they could impose sanctions on other companies for dealing with said company. They have an enormous amount of power to make sure said company can never deal with anything EU related. They have tried to sue companies in the US for not complying but no outcome for that is known.
That is why you see the cookie notices and general compliance, but also if you’re a relatively small company it’s actually not that hard to comply. It gets exponentially more difficult the larger you get but if you’re that large than you’ll definitely be dealing with world economics, including the EU which gives a lot of incentive to comply.
if actually read up what GDPR is
I have and was a part of my curriculum. Bit arrogant innit