Glasses tend to correct this as well without you realising it while contact lenses don't
Is that really true?
I don't know - a real Q.
Most people who need correction do have some astigmatism, and in fact in a lot of cases (myself included) correcting the astigmatism alone (which on glasses is done with a cylindrical surface on the back of the lens) improves vision so much that no other correction is required to pass 20/20. In fact, glasses which didn't correct astig would be hardly worth having in my case.
On spotting other planes, I know this is not the often trotted out story, but actually
they are hard to spot. Lookout is far less effective than most people think, and it is not for no reason that the RAF, following some fatal mid-airs, have just spent a vast amount (my guess: £20-25k per aircraft) fitting TCAS to all their Grob trainers. And these are the cream of the cream - instructors or pilots under training.