If This Doesn't Prove Turrets Are Too Weak, Nothing Will
https://www.youtube.com/watch?v=xoLksRHjiio
My turret had 2/3 health and I left to go get blue buff and come back to see that Heimerdinger who only has Doran's Ring took 1/3 of my turrets health without using his turrets. If you pay attention his turrets are in the same position when I come back except he placed an additional turret, so he didn't use them to damage my turret.
A Heimerdinger with just Doran's Ring took a 3rd of my turrets health in the time it took me to get blue buff from my jungler without using his turrets.
At this point if you recall after level 6 and don't have tp your turret is gone, even if its full health and your lane opponent has no real items you can't leave lane for any reason or else your turret will be taken or close to it. I left to get blue buff and my turret lost 1/3 of its health, if I had recalled it would have been gone, AND THIS IS AT ONLY 9 MINUTES IN.
Also Blue Buff's hitbox at 16 seconds...my bomb goes right through it lol.