When selecting options for baths for disabled or elderly family members it is a good idea to look for disabled baths that are ADA certified or compliant.
One should look for the statement
ada c section 607 bathtub certification for bathtubs
Keep in mind, the certification applies only when the disabled baths is installed in the proper manner by a certified plumber. This rule usually also applies to any manufacturers warranty that is offered with the bath tub or walk in tub.
Things to look for include the height of the tub, which usually is 17" for best movement from wheelchair to bathtub. The options to consider are whether the door fold in or out and what luxury or therapeutic options you might want included.
Common features include:
Digital water control that keeps water from ever reaching scalding level
inline temperature control, whirlpool bath options