The only time I charge is when I shot nudes...ill shot clothed for free as long as drives not far and if it is the gas is good enough....now if its out of state the room food gas will usely cover expenses

I pay models because I can afford to and because it gives me access to larger talent pool for me to practice my art.  When I pay I don't have to worry about how quickly or if I  ever get images to the model.  When I am busy that is a big deal.
Paying also increases the likelihood that I will shoot with an experienced and reliable talent.

I have lots of sports teams, seniors, families and toddlers that are willing to pay me to take their pictures.  In those instances I shoot what they want and when they want.  I take some of my profits and spend it on some of the most beautiful people on the planet for a couple hours of watching them work their magic and helping me explore new lighting techniques and concepts.

Seems like a great deal and it works great for me.  I don't give tinker's damn how the economy of it works or doesn't work.  Ain't my problem.  My probelm is already worked out.

I didn't start shooting models to make money on them.  I think anyone living in a podunk town like mine in the middle of Missouri and with a goal of being a model photograper super power has lost their ever loving mind.  There isn't enough work around here  to build a dynasty in the modeling business. 

All of this IMHO.

I am always open to hearing rational discussions from those who believe otherwise if they can the guy to leave your door unlocked so you can sneek to the common room and get on the internet after the day shift goes home.

Modelling is a performing art, much like dance, acting and music.  Most who dance and play don't get paid, its not a job, it's their hobby.

95% ++ of internet models are amateur.  They will always be amateur. They model for fun, to meet like minded people, to make art and images. That's all. Same with photographers.  They get together and do their thing, trade time for photos. That works, has for decades. 

Then there is the remaining few percent. Professional and semi-professional models.  Some photographers and artists prefer to work with amateurs and some prefer to work with professional models.  Supply and demand applies.

Independent models charging escort rates probably are escorts, provide a look - no touch escort-like service that some call exotic modelling. Supply and demand applies too.  Many are dancers too.

Artistic models sometimes charge out but at more modest rates, its the second oldest profession.  2/3 of artistic nude models I work with prefer not to charge, they choose to work as amateurs, be part of an art project. They work TF*.  They like nice quality reasonably large prints.  B&Ws, etc.

Experienced professional models doing commercial type work typically work out through agencies, get paid typical agency rates - clothed, lingerie/swimwear, and partial/implied/full nude rates. Garments, makeup, styling all provided. If you are a professional photographer doing a commercial job for a client, its likely you will pick a reliable agency model for the job. Everyone gets paid hopefully.