Thing is, it's just not that easy to get a ride in normal circumstances. The majority of women want more than just sex. Obviously there is the exception but they are few and far between. Dating is way easier now with Tinder, Plenty of Fish etc, but even that takes huge effort and commitment. The texting back and forth, going for dates, all that can be stressful and overwhelming after you've done days work.
Even the likes of Fabswingers, a swinging website. You would think sex would be dripping clean off the walls of that website. Instead, you've got thousands of guys bombarding the few women there with messages, so again even something like that takes hours of work. So it's not hard to see why even single guys visit escorts. No hours of ground work flirting. Just turn up and get your rocks off.