> However, the last 7-8 years in the US have shown that (at least in politics) rules need to be spelled out. We had a bunch of informal agreements of what people in certain positions should do or not do, but as we have seen someone will eventually come around and look to test the limits.

People coming round to test the limits is fine, the problem is that in the US parts of the ruling class has decided the (short term) benefits of tolerating severe transgression to those limits is worth it, in effect simply removing the limits.

The problem is simply that limits don't work if there is no the willingness by the people in power to enforce them, and this regardless of if them are informal or formalised limits. Many things things Trump did were simply illegal, but since Congress didn't impeach for these crimes they just become "controversial actions".