Some of the web sites look exactly the same except the pictures and rates are different.

So what are the reasons for this? Are providers just copying another's website or is there a list of standard layouts for provider web sites that everyone seems to use?

Cut and paste hosting services for those who can't do their own or those who don't want to have them done professionally.  I can think of 4 hosting sites off the top of my head.

If you check to see who the webmaster or web designers are you will find that some of the higher end sites are from the same designers.

Many of the more common (lower end) sites are "free" escort sites that the gals can maintain (or with some help from a "friend") themselves.

It would be rare to find a lady that has a customized site done only for her.

Some web designers give clients (providers) templates to buy from but are usually derived from a similar style. It's not necessarily a bad thing as a good website (user friendly, classy looking, etc) means a more credible provider. Veda Designs is really great!

When I look at a provider's website, I'm interested in content, not presentation. I want to see photos that show what she looks like and read about her rates, screening, contact info, etc.

Most templates do a good job of making all this available. And since I've seen them applied before, I know where to find everything. Custom designed sites often obscure what I'm looking for without adding anything I'm interested in.