They just want to make money......
I tried active shutter glasses for 3D tv for about 3 minutes at department store I was underwhelmed by the experience but as well it took at least 1 hour for my depth perception to return normal. I loved Avatar in 3D but I also noticed a growing number of warnings being posted from brain specialists about loss of perception depth for many people and suggestions that patrons be warned about the dangers of driving immediately after 3 hrs of altered perceptions in a 3D movie.