It really is about driving culture. It is very obvious that f.e. italians think 30cm distance is plenty. Very different from france or switzerland or everywhere really except croatia where i have ridden. Netherlands is a whole different beast since they really seperated the traffic. Dutch drivers in on holidays abroad are some of the worst offenders though in my experience, which i found surprising, always thought that they are maybe not used to share roads as much, or because they don't know how big their trailers / RV's are.

In germany it is now part of the traffic law since 2020 that you need to keep 1,50m distance in cities and 2,00m in rural areas. There is also the open bike sensor citizen science project which measures distances, so you can show actual data about problematic areas or general (non)compliance, which i think is really cool. Pretty sure the distance kept got bigger in the last years here due to the law and also i think it being in the news with open bike sensor etc helped.

Of course you still have some drivers keeping way too little distance.