Are bike repair shops averse to changing chainsets? I have found that bike shops will happily replace cassettes and chains.  In contrast, even if a chainset is showing wear, they will be unlikely to change it. My brother just went to get his bike serviced and I noticed that his chainset is shark toothed and they only replaced the chain and cassette.
Has anyone else noticed this? If so, do you think there is there any reason for this?
The chainrings last a long time but are expensive, and a lot of cyclists are surprisingly tight when it comes to servicing.
Worn rings should be replaced when necessary though, otherwise the shop is throwing away good reputation and good income.
The teeth on many modern rings are often quite pointy and shaped, making identifying wear that much less straightforward.
I'm sure there's no one true answer.