Mostly it's about upbringing. People are taught to have expectations for themselves and they strive to fulfill them. 15h would be bare subsistence for most, and that's not good enough. The minute they can live their expectations without work they usually check out; e.g. 45 year old "retired" government workers bankrupting their muni/county/state with union negotiated pensions.
Defined-benefit pension schemes are a problem because now, with the baby-boomers retiring, we're finding that we can't afford it. Many people can expect to live to 100 - that's 35 years of retirement after 45 years of employment when their employer probably only set-aside 10-15% of an employee's income for investment in the pension when it should have been 25-30% - so now the younger generations are paying for it - by using revenue generated from their activities to pay for the defined-benefit schemes which cuts into their salaries - and making them work longer years to make up for their own contributions.
Do we have an actual source for this yet? Anecdotally, I still see about 7 out of every 8 deaths in my social circles occurring before 90, with a notable number before 70.
Mostly it's about upbringing. People are taught to have expectations for themselves and they strive to fulfill them. 15h would be bare subsistence for most, and that's not good enough. The minute they can live their expectations without work they usually check out; e.g. 45 year old "retired" government workers bankrupting their muni/county/state with union negotiated pensions.