If the Gov't considered air travel to be a major hotspot for covid they would probably have banned it. They probably looked at the way mask wearing has been enforced by the airlines and airport, which is far better than in pubs & bars. People do not tend to raise their voices on aircraft unlike pubs & bars and this is another well known spreader of the virus. Shouting across a crowded pub to your mates is a given in most city centre establishments on a Friday night. There is a world of difference between airports & pubs in this respect..