[jhall1468]

A large number of medium to large businesses do. The overwhelming majority of small locally owned businesses don't. They still represent the overwhelming majority of sales.

Furthermore, big companies all implement their own software or purchase a variety of systems, some of which have API's, all have different API's and none have open API's.

A system that can speak, universally, to every Salon (or even say... 60%) is actually considerably less complex than the universal API you're calling "easier".