My understanding is that the excess cost isn't so much the safety device itself but that cheap, flimsy table saws can't handle the extreme torque created by stopping the saw more-or-less instantly, so the device is limited to higher end equipment that's heavier and has better build quality.

If it costs 200$ to add the device and modify the saw to accept it and the original saw cost 300$ you've got a pretty massive increase. Also from some deep dive I saw apparently SawStop has basically cornered the entire premium market and the only market left for other saw makers was the low end range.