My advisor is recently-retired, I believe. I think he put away a fair amount for retirement in addition to having a pension, in part because he had his hand in a variety of different income "pots."
I think it's just that most folks in the US, regardless of profession (barring a few), are pretty bad when it comes to saving for retirement. That, and maybe folks in psychology stick around longer because they enjoy the work/intellectual engagement, and fear they may lose that with retirement...?
Edit: In my case, I've started setting aside since getting a "grown up" job via the equivalent of a 401k, but need to up my percentage contribution at some point to catch up for all those years spent in grad school. I'd also like to establish a few other income streams within the next 5-10 years (e.g., rental/investment properties, go in with a friend to buy a franchise or other small business, etc.), once I've had a chance to get my career a bit more settled. I very much enjoy what I do day to day, and hope to keep doing it for quite some time, but can tell I'm already feeling a bit antsy because I'm so used to their being a well-delineated "next step," which is no longer the case.