the point of the op is to question whether all of the travellers in and out of Heathrow are essential workers.
I'm sensing a lack of understanding of what is actually allowed.
You do not need to be an essential worker to go in or out of Heathrow.
Certainly as I understand it HMG rules allow any worker to travel out of England for work purposes if they cannot work from home. ..sounds like that's people like Eileen
They can legitimately arrive back into the UK after that work...it's only really then that the essential worker bit kicks in:
Normal workers will have to self-isolate.
Essential workers may not have to self isolate (there's a list)
Anybody arriving from a Red List country has to go into managed quarantine...
It's worth mentioning you may also be seeing some workers/families of workers who have been out of the country long term but repatriating at the end of contracts/who have lost jobs abroad...
So all the above can legitimately be in a queue seen on TV, and it will be several thousand a day ATM, verses a normal day at Heathrow when it could have been 50-100,000 ish..
I'd seriously suggest whilst there might be a few "on their jollies" it's very few and there's no real way of telling who is who from TV or still images of queues...