These days it’s not unusual for someone on the way to work to receive a text message from her employer saying she’s not needed right then.
If businesses are going to this there should be laws governing it. I don't think someone should be on their way to work before they get a call saying they are not needed that day even though they are scheduled to work. I think you should at least get a two hour notice. If you show up for scheduled work and they send you home they should have to pay you for your trouble. Not fair to workers at all.