Hamstrings always get the shaft. It is so much easier to work the quads than the hamstrings. You can do squats almost anywhere. Heck, if you hold in a squat position for 30 seconds your quads will probably start to feel the burn, but hamstrings curls are a little harder. You need some kind of resistance besides your own body weight for hamstring work.
With the shoulder bridge all you need is your body weight to access the hamstrings, but you have to be lying down. You can’t do the exercise while pumping gas, whereas squats you can do anywhere at least somewhat innocuously.
Lunges work the hamstrings, but also the quads.
I’m just feeling a little bad for my hamstrings today. I know they need a little more attention, and I wish giving them that attention was as easy at doing heel raises to strengthen my calves. So for the moment, I’m just sitting at my desk isometrically squeezing the heck out of my poor little hamstrings so that they don’t start to think that I like my quads better.
