Older machines, and some less expensive/midpriced VMCs do not have rigid tapping. So, no, it isn't standard, and is usually a 1500-2000 dollar option on a lot of machines shops buy in quantity.
Rigid tapping is popular in the industry because there are certain high speed/high performance form taps that will not start in a floating tap holder. You must have a machine that does rigid tapping to use them.
Additionally, higher practical tapping speeds are possible on a rigid tapping cycle. On floating taps, the spindle and Z axes deceleration aren't completely synced, so at higher speeds, the floating tapholder sometimes winds out completely and breaks the tap off. With rigid tapping, the deceleration of the spindle and the Z axis are in sync all the way from full speed to dead stop, keeping the tap from breaking no matter how fast you try to tap.