The UK's ICO also has a good structured summary: https://ico.org.uk/for-organisations/guide-to-the-general-da...
In general I agree with the sentiments in this article. I've probably spent a total of three to four days reading around the GDPR and I don't really see what's special about this law other than it's imposing decent standards on what was in effect a wildly unregulated industry in people's personal data. If you have a broad distrust of any government activity then I suppose any new laws with "fines up to €X" might feel like "I run a small site on a Digital Ocean droplet and I'm at risk of a €2m fine out of the blue." But that doesn't make it true.
In rules-based regulation, all the rules are spelled out in advance, and the regulator is basically an automaton once the rules are set. In principles-based regulation, the rules are extensive rather than complete and you expect the regulator to have some lattitude (and, if the system is well designed, a mechanism of recourse if they do something stupid).
An advocate of rules-based regulation would say this can make regulators unpredictable and capricious. An advocate of principles-based regulation would say it is an important safeguard against "rules-lawyering" and regulatory capture (especially the kind that ties new entrants up in check-box compliance that doesn't actually affect your business because all the rules have been worked around).
A classic example would be the time PayPal tried to tell the UK regulators they shouldn't be regulated like a financial institution (which is a claim they successfully made in the US). They pointed to chapter and verse of the relevant law, and said that according to subparagraph 2.b.c(iii)... and the relevant regulator essentially told them "shut up, you keep consumers' money for them and will be treated accordingly". As a result, the worst "PayPal took all my money and I can't get it back" stories generally do not come from the UK. (And when they do, they are accompanied by referrals to the Financial Conduct Authority, who have teeth.)
You can approve of this way of working or not, but the GDPR is a principles-based regulation, and you'll have to engage with it on those terms.
Given that description, after a couple decades working in some and dealing daily with the acts of other agencies who which issue and apply regulations on the US, let me assure you that the regulatory system in the US is nothing at all like “rule-based” as you have described it.