To fix the issue the doors need to be removed bottom of the jambs cut and reset the door.
Interior door height off floor.
The standard i use is 1 2 over finish floors 3 4 is acceptable.
The additional room allows for a 3 4 inch top jamb a shim.
Most entry door frames have a piece of lumber below the door and combined with the metal threshold will raise the base of the door off the concrete or wood sub floor by approximately 1 1 4 inches as shown in figure 2.
I have never seen a door set with that big of a gap unless it was to get past floors that were not level.
The standard height of the rough opening for a door is the door height plus 2 5 8 inches.
Interior door height off floor.
The height of common doors is 6 feet 8 inches.
I just took a quick look at some of standards and regulations governing door undercut which is the distance between a door and finished floor as opposed to clearance which is door to sub floor.
Figure 2 floor relative to entry door.
That is a lot of room for unlevel you have there.
The awi gives no minimum but a maximum of over 3 4 is unacceptable.
Installers typically drill the hole centered 36 inches above the floor if not specifically instructed to do so differently exceptions to the rule include doors that provide egress into swimming pools or other water features.