The cure for a lack of legs is typically prosthetics with extensive therapy. Incredibly expensive and labor intensive.
The cure for amputated legs while being poor is a wheelchair; not as easily managed without additional space when parked, and if there are no ramps up to your building, your business is effectively inaccessible.
But ramps cost extra money. So do wheelchair accessible curbs. You need more space in the isles, specialized bathroom stalls, special door handles, support for someone closer to the floor at your counters... Lots of things we take for granted today, but which didn't exist for many years before the ADA.