Reason about 60 years limit in France...
Only one: lack of work for pilots, wich led pilots union to think it was better to give an opportunity for flying to people with a great need for money to sustain themselves and family, than to have the eldest continue flying while they could retire on good financial terms. A law was passed in French Parliament without opposition.
About the taxes payed by pilots: their used to be a special advantage (reserved to some categories of tax-payers: all crew members, journalists, artists....) to substract a big part of their declared income, considered "professional depense". This advantage disappeared years ago, but crew members got the possibility to substract the "real" professional spending as can do many independant workers in France .
There is a complicated regulation about it which takes into account the places where they travel, duration of travel, part of PC buying and using, car,...et al.