When your young and free from responsibilities its easy to hook up with a mate to go down a proper gym ( not leotards and chatting on the machines). A bit of peer pressure is always welcome especially if you want can't be arsed but you have to go as you've arranged to meet.
Fast forward to a having a family, a demanding career with little free time. Put your mates in that arena as well and its impossible to sort out regular effective training with a partner.
Using a PT is a quick way of locking in good gains and creating a bit of pressure. The big thing to avoid is boring sessions and a good trainer will move things along keeping sessions interesting but effective . Ok you could go at it hammer and tongs with a little knowledge and see where you get? It depends whats more important. Your cash or your time? Thats the bottom line.
I never thought i'd ue a PT but it does bring it's benefits and I agree it does sound a bit iffy. That said when your out on the bikes and you dropping our mates on climbs all the negatives drop away.
I've used a PT for just under a year, seen some great gains and now I'm considering a move to the dark side and joining a road club to build some serious miles in my legs over winter.
And to qualify my comments I purchased an old cateye stadium when they were new so I could go night riding by myself as all my mates thought I was loopy as in their minds ' you could have joined a gym for that much" and night riding back then was considered "strange". One thing is for sure. Never say never