On the subject of retirement, I don't understand why that is something that people aspire to. I want to work as long as I can.
Yes, but in Spain you get government benefits and it is not a private company decision. Civil servants do it all the time.
The original purpose may have been to get older employees to move out of the way for younger ones, but the effect is that people go into prejubilacion (or even pre-prejubilacion, believe it or not, where their duties are reduced) and essentially get to retire at 55. Don’t forget, many of our civil servants in the US can retire at 45 or after 20 years on the job, so this is not unique to Spain.
However, it is a big problem for Spain because it is so extended. In addition, there is a huge underground labor market, since most of the “prejubilados” secretly continue working (for somebody else or perhaps they have their own businesses) and of course do not report their income or pay taxes on it.