You generally don't see handrails in football stadiums, but for me they make a lot of sense; particularly in modern stands like ours where the steps are quite steep and quite a few elderly fans and children use it.
I'd imagine though that the cost may have something to do with why we don't have rails though. To kit out the PMG alone would probably bring a four figure bill. Swapping seats to a lower row would probably be a more realistic solution for those with mobility limitations.