There's more to primer sensitivity than just the hardness and/or thickness of the primer cup. The priming compound itself also plays a role.
For instance, Federal uses a more sensitive formula for the lead styphnate in its primers than CCI, Remington or Winchester do. I believe that this is why the Federal primers are also packaged differently, since they're more susceptible to shock.
The problem with non-toxic primers is that they can't use lead styphnate (nor, for that matter, the old mercuric priming compounds in corrosive ammo). Finding a non-toxic priming compound has been the big stumbling block in producing totally "green" ammo.
By the way, I've had misfires with Winchester WLP primers, too.