Since I don't carry gear on trips, I always rent. I have never had rental gear that comes with retaining devices for anything besides the octo, and sometimes not even for that. I still dive danglie-free because I take retractors and various clips with me to create my own setup with the rental gear.
The average vacation diver is likely unaware that rental gear just doesn't come with that stuff, and may well assume that if it was necessary, the shop would put it there. Before I began taking my own stuff, I used to cradle the SPG in my folded arms as I dived but I don't think I've seen many people make that kind of effort in gear without the necessary clips, etc.