There's nothing wrong with reinforced concrete, but the incentives to produce long lasting buildings are not there. The cheapest bidder will generally win and their building will last the "design life" of the building, but often not much more. The simplest way to change this is to extend the design life, which would result in stainless steels or another more expensive material being used in this application.
Just FYI, on a ‘plan and spec’ construction project, all material is specified by the architect and engineers. If the project specs say you have to use stainless steel rebar, then even the low bidder will have it included.
I've noticed manufacturing companies like big auto will try to solve for this by creating more specs for parts provided by suppliers but that's a losing battle as its always a race to the bottom. Plus now you need large testing teams to verify parts meet all these different specs. Maybe some percentage of the parts do - what do you in that case? The whole process can be a mess.
Construction specs often include “Allowed manufacturers” to limit your choices to certain vendors, which theoretically means you get quality material. For stainless steel, sometimes they’ll specify which alloy you need to use (304L and 316L are the most common) You certainly could submit the specified manufacturer’s product and then switch it out for a cheaper option, but if you’re caught, you could be forced to correct the work with the right material or be financially on the hook for another contractor performing the work. It would be up to someone else to notice that the steel contractor isn’t using the specified material, which may never happen.
The ‘use less of it than needed’ problem would ideally be caught by an inspector, but they certainly aren’t perfect.
Here’s a link to Cleveland Clinic’s electrical spec, if you’re curious how detailed they get: http://portals.clevelandclinic.org/Portals/57/2012_Elec%20Sp...