"We're making accomodations for the disabled because, on average, 100% of the population is disabled at one time or another."
Everybody drives the same roads ("Why would I pay to maintain Smith Street? I've never driven on it?"), some people REALLY need a firefighter in an emergency.
To the extent these impact public buildings, I think this is a good thing. Just like I think public employers should not be allowed to discriminate based on age, race, etc.
But in both cases I would argue that private companies should not be held to the same standards.
Firefighters could arguably be a public good in that they are (approximately) nonrivalous and are definitely nonexcludable. In addition, fire fighting as a public good prevents the free rider problem that would likely exist with this service in the private market.