I think you’re reading it wrong. In California there is nothing stopping you from getting your eyes examined by an optometrist, getting a written prescription, walking over to Lenscrafters and having them make your glasses. Most people don’t, though, they just order their glasses right there in the same office that examined their eyes, because it’s convenient.

The law is saying that if you are Lenscrafters or a strictly an optician’s business, you can’t wall off a room and rent it out to one or more optometrists as independent contractors to run an optometry clinic on your premises. If you want to do that, your entire business must be an optometry clinic, not just an optician’s business. Optometrists and their clinics are regulated by the state, and must have special business licenses, malpractice insurance, be subject to inspections, etc. The Lenscrafter-type companies want to be able to offer the same service (one-stop shopping) without having to deal with the regulations, licensing and insurance - instead fobbing that off to the independent contractor optometrists renting the adjacent room from them.

Optometrists actually make most of their income from selling frames and lenses. As Aligarr points out, exams are covered by most health plans and by Medicare and Medicaid, but that means therefore the reimbursement for an exam is not that much. An optometry office has to not only deal with the regulations and insurance, but keep an inventory too. This is why, if you do choose to get your prescription filled elsewhere, the optometrist’s office will usually charge you a fee for giving you a written prescription to take away with you.

The point is that optometrists believe that if Lenscrafters can functionally, even if not “officially”, offer the same one-stop service, before long the traditional optometrists offices will go out of business and all optometrists will be forced to work as contractors to the big boys, rather than being able to run their own private practice.