There are a few reasons for this and nothing at all to do with self racism or discrimination.
Try to book a holiday to Turkey (well I know this pertains to
Icmeler and Marmaris) with a UK travel agency with a Turkish person as your partner and they cant do it unless they hold a British passport
All these low priced apartments that travel agencies contract to are for the British market
Nowhere else could you get an apartment that sleeps 4 for for a few quid a week.
Our own country advertises £9 per night in a certain
hotel chain and I have gone scabbie eyed looking for this but the norm is £55 up the North of UK but look South and prices are well over £100
Anyway I digress.
The contracts are done for the British market to attract UK people with lots of holiday spends to spend at that accommodation.
A Turkish person will not spend, he will go out to buy food and drink and relax in his apartment so they pay more as they wont spend (thats another reason)
Lots of places will also not allow Turkish people to stay because they work in the resort and then also bring their friends to the pool areas and into the complex so security reasons then appear.