In my experience Ryanair don't worry too much about hand baggage on departures from the UK but are obsessive about both hold and hand baggage on flights into the UK. I have always assumed that the majority of their pax are Brits and they expect to clean up on excess baggage charges on returning holiday makers. (their hand baggage checks always occur after hold luggage has been checked in so no rearranging can occur.)
BA have always appeared to be more relaxed although I guess that may have changed recently and most of the EU airlines I have flown on seemed to be totally unconcerned so long as hold baggage is not too much above allowed weight.