LDS folks are required to work on Sunday in many instances. Sometimes they can't help missing church.
This is a matter of how one defines "keeping the Sabbath Holy" on a personal level. The Sabbath is accepted throughout Christianity as Sunday, of course.
Some areas close down completely on Sunday, or in many instances, have much shortened hours. It's not just a religious thing. It's about economics.
Sabbath day observance is one area that has driven me crazy for years. So many meetings for everybody, firesides, byc, etc. Then all the people who watch tv on sunday tell all the people who watch the superbowl that they shouldn't do it. All the people that work say you can't play video games. Everybody is all over everybody else. "You bought gas on sunday! You're going to hell" etc etc.