You have made the fatal error of assuming that a western wouldn't make use of CGI. But setting aside the use of CGI for a moment it is a simple fact that costume pictures cost more to produce than ordinary pictures. TRUE GRIT cost $38m to make. If it had been set in modern day America -- using the same cast and crew -- the picture probably could have been brought in for something around $25-$30m. It's this 20%+ increase in manufactured cost that makes a western less attractive to studio bosses.The expense of a Western = horse charges, are nothing compared to sci-fi post production CGI expenses. So I discount that view.