I have only taken one flight since March and all passengers seemed to abide by the rules apart from the rush to de-plane on arrival at Gatwick. The flight wasn't full so I wasn't sat next a stranger with no mask on, and altogether the experience was reasonably pleasant. At no point on the whole journey from check-in, security, boarding did I feel concerned with social distancing etc. As the flight was from an area/country on the UK quarantine list like Spain & Portugal the airlines will struggle to get decent passenger loads.
I sure for every nightmare scenario the LTNman can quote there are plenty of flights and airports that are making the experience as comfortable as possible. Unfortunately the media and scaremongers only pick up on the worst cases, so Joe Public never gets to hear about the good experiences.