That could become a long thread.
The rotorheads of model helicopters are rigid rotor heads. An R22 has a rotor that is semi rigid teetering rotorhead, which means it has hinges that let the blades flap up and down. This is needed, because otherwise you would not be able to fly very fast. The lift difference between advancing and retreating blade would make the helicopter roll and crash. You would have to compensate this manually, but that would make the controls more effective in one direction, than in the other. That is why hinges were added to rotorheads, because then the blades can correct that for themselves. The hinges and the rigging change the angle of attack on the blade constantly when it goes around.
In a model helicopter you don't need these hinges, because the speed difference between advancing and retreating blade is relatively low and easily compensated by the controls . You also don't care about vibrations, because nobody is sitting in there and a model helicopter is much stiffer and sturdier than a real one. And it will not fly for thousands of hours, therefore fatigue of components isn't really a thing. And if it crashes, because something breaks, you buy a new one. In a helicopter the rotor itself does create vibrations, because the center of rotation moves, due to the flapping of the blades and a few aerodynamic reasons. Therefore virtually all helicopter rotorheads have some sort of damping incorporated in their design.
By the way, no real helicopter can actually fly upside down, which means hold the altitude, because they don't have negative pitch. If you see the BO105 on its back, it is actually falling down.
And yes, some helicopter have rigid multi-bladed rotorheads, but in this case, the blades have virtual hinges. Which means, that the blade itself is meant to bend in a certain way to compensate.