I can't speak for everyone, but my garage and basement slabs were done with wire mesh. They also offered to use fiber mesh concrete, but didn't want the hassles when it came time to coat the floor.
Probably not unless you specify it. You region where you live my be a deciding factor whether or not the contractor adds to automatically or requires you to ask for it.
Any concrete, anywhere, needs steel.
It is very strong in compression, but very weak in tension.
It cannot stand up to any bending stress without reinforcement.