Just my experiences, which do not represent the mean, mind you.. just that in the several occasions I've brought a USB cable and plugged in - my phone doesn't charge.
Not that I really cared... My phone is generally 80% charged or better when I take to the course. I keep it on silent mode, and I'm never disrupting those I play with.
I do enjoy an occasional bluetooth playlist when play my home course, but I tend to keep my phone in "do not disturb" status as to not disrupt those I play with.
Never had an issue really. But if a facility is going to promote that "perk" with the latest and greatest features of their carts - at the very least they should make sure it functions accordingly.