Err... no. The local authorities' rules and regulations are the minimum. There are countries where the regulator or lawmaker prohibits people other than the flight crew in the cockpit during the flight. Every airline then has to abide by it. The UK is such a country: no airline operating to a UK airport (or maybe it's even in UK airspace, but how would they check?) can have a person other than crew members in the cockpit. Air France, despite allowing cockpit visits, is not allowed to allow them when flying to the UK:

Then there are airlines, who may have rules that are stricter or less strict than what the regulator imposes. BA, the US carriers, and many others have a rule: nobody other than crew members in the cockpit. And they abide by it, even when operating into a country where the local regulation does not prohibit it. For instance, British Airways flying to Germany: no visit in the cockpit. That's because it's a BA rule, not a German rule.

Thus,to have cockpit visits allowed, both the country and the airline must allow it.

Lufthansa is not relaxed about this at all. Strictly no cockpit visits during the flight, despite this being allowed in Germany. AF and LX are two airlines that I know allow cockpit visits.