I've seen alot of SMs with halo seats.
I own one.
Step 1: Survive the impact without injury.
Step 2: Exit the vehicle.
I believe a HANS and a halo are important in making Step 1 a reality. Having removed the wing window on the driver's side, I can climb out past the halo seat with the door closed. I guess there are always side nets for those who need a bigger opening.
I support the requirement for SFI/FIA head & neck restraint. There are several to choose from. If there are rapacious profits to be made, invent one that works, get it certified, produce it, market it, defend it against lawsuits... Then reap the massive (?) profits from the sales of a durable niche product that your customers will replace, ummm, if and only when it has served to save their necks.