Yeah.....but you have to understand their "on the side" training is much harder than most people "back day". & you also have remember the giant amount of good mornings, rack pulls, deadlifts from blocks, and front squats they typically do as well. There is a LOT of indirect volume, which many people just don't realize. I mean, you're talking about people who can make an entire DAY out of deadlifting:
Deadlift to 3RM, + 2 down sets
Rack pulls 5x5-8
Good mornings 3-4 x 8-12
Kroc rows x 2-3 sets
Seriously, thats a shit ton of back volume. But most people see a leg day. It would be different if it had been deadlift + lots of lunges/single leg work...but thats not how powerlifters usually roll.
So yeah. If you put down weekly deadlift and goodmorning volume like that, you "only" need 2 back exercises on each bench day.
However if you look at the weekly volume of back work for a lot of elite powerlifters, you'll see that it is at least comparable to a lot of bodybuilders back days, just spread across more than one day.
If you want a back day, one I used with success was:
face pulls x 8
T-bar row up to a 5RM
Band pull aparts x 10 , the three exercises are done as a triple set, and both the face pulls & the pull aparts are held for 3 second EVERY REP (this means lighter weight). The T bar rows are there for overload, Yates style, so no need to hold the contraction there, just move the weight.
2 sets Kroc rows OR 3-4 sets of high pulls OR 3-4 sets chin ups.
If you are looking for a way to incorporate back work into an upper body day or just across the week, you can start by doing 4 sets of cable rows or pulldowns, or facepulls as a part of your warm up for every gym day, lower or upper body. Stay away from failure obviously if you are going to use it as a warm up. Then on your upper body days also do at 2 back movements (preferably different angles & also different exercises from your warm up). Do one heavy for 6-8 and the other lighter for 8-10. And make your leg days heavy on back work, like goodmornings, rack pulls, reverse band deadlifts, snatch grip deadlifts, high pulls, or whatever.
To the OP--your major problem is that you only have 3 back exercises in the entire WEEK! How are you going to build a big ass back with only 3 exercises in a week? I do it, kind of.....but I do one or two of those exercises EVERY time I am in the gym as part of my warm up (power snatch, leaning row to neck), so I end up getting a bare minimum of 6 sets 4 days a week. thats 24 sets. Typically I get more.
I could never make it work only doing 3 total exercises, 2 on one day and 1 on the other. You nees to focus on it, not leave it as an after thought. So. You, OP, need to do a) more deadlifting and rack pulling and goodmornings and b) you need on top of that to either do 3-4 sets every dzy in your warmup + do 2 exercises on bench day, or do a dedicated back day separate from deadlifting.
Sorry for typos, on my phone