It does surprise me that many of the airlines appear at least to be less favourable to older applicants. I've known people aged 50-55 change career into a safety critical industry and perform as easily as well as and in many cases, better than, people in their twenties.
At the end of the day, if you've got a house and family, you're presumably going to be satisfied with a nice regional base, a decent work/life balance and a decent salary. I've noticed many of the low-cost/regional operators lose a lot of their younger folk to the world of BA/Virgin and overseas operators. Upping sticks to London/SE or commuting to start in a very junior position on a heavily seniority-based roster is presumably not too appealing with a family and kids in tow. Surely it is better to recruit a 45 year old who's going to stay for 15-20 years than a 20 year old who will probably move after 4-5 years?
I do wonder, does previous safety critical experience lengthen one's shelf-life from an airline's perspective? Is a 45 year old ex-copper going to have an easier time in the job market than a 40 year old ex-accountant?