Good question Vanica..
Time and opportunity for the most part but $$ plays a part too..Oh, I should say Im sort of long in the tooth so recharging the energizer cells also play a part..
Women here sometimes think they are not chosen and someone else is...that is often just not the case. Add to that logistics issues, getting from point A to B around here, life's issues suddenly interfering with hopes and dreams..
and on and on..
Heck there are new girls every week that look very appealing plus the existing list I would like to meet but it aint going to happen in most cases...Maybe in the next life..lol

mostly location- there are a few traveling ladies that I have had my eye on, but for whatever reason when they visited schedule didn't work out- then there was the one years ago that started out as a provider (about 400 -450hr) looked great, but no reviews so I waited not wanting to spend that much on a non-reviewed provider- a few months later she did some porn, now does a fair amount for Brazzers and raised her rates to 1000

You're one of my "unicorns"; it's all about making it happen; sometimes things work out, but there's no timeframe- opportunity and ability have to coincide  

No Unicorn here.  The only thing that prevents me from seeing a provider are poor reviews or no reviews.

For whatever reason...my  unicorn wont return my emails....sad.

have had a string of bad luck with Touring young ladies recently with either no response or their in town and I am out of town.  The no response thing really pisses me off.  One recent event was an attempt to contact her through her p411 account to get a date and provide references too.  After numerous attempts I moved on to a local agency that I love to deal with.  They always respond.