I'm working in a B2B telecom and I haven't seen that level of conservativeness, although in general I agree that they
are conservative. But it's a wonderful place to work in many aspects: it's stable, pays well, and in general less clients means less headaches and a more focused development.
They don't immediately adopt new technologies, but frankly, nowadays I see that as more as a feature than a bug (although once in a blue moon I wish the delay in finally adopting them, when they have been successfully proven themselves, wasn't so long).
The most glaringly conservative aspect of my current job is its very rigid adherence to process. Again I must say that, having worked in places where it wasn't the case, I'm so glad that process is followed strictly.
The big problem with this job is that I've acquired a ton of domain knowledge that probably won't be useful in another job. This means that I need to keep other tech skills (algorithms, programming languages...) much more finely honed. On the other hand, I've acquired top notch documentation skills.
EDIT: I also can confirm that there is plenty of >40yo people here. Definitely a good place to be when you reach that age, although I'm only in my eearly thirties. I've found also a high level of diversity in general, which is very, very good.