Are the Mini Hobby Models 1/35 Scale Russian T-72 Tank With KMT-5 Mine Roller and Tamiya T-72M1 the only kits with flex track
Yes, as far as I know. The other T-72 kits are either single link (Trumpeter) or workable snap links (Amusing Hobby).
The ancient Esci kits are link and length styrene track, and the ancient Dragon kits (now offered by Zvezda) were single link tracks as well. These 1989 vintage kits are not accurate.
Mini Hobby is one of Trumpeter’s brands, but those kits are old, crude motorized kits, and may have misproportioned hulls to accommodate the motor.