Just flew IAH-MUC on UA as well. Before boarding announcement made that masks required, handful of passengers grumbled up to gate desk and received masks. On board general announcement made. All crew wore masks on board (most did not in IAH terminal). Most passengers wore masks most of the time. No individualized prompts or reminders in flight, that I saw.

In German airports I think maybe more masks than not, but many people no masks.

Overall I do not pay that close of attention to this issue, so maybe some people just did not mask on board and 'got away with it', but the above is what I noticed and recall.