Sounds like a union gig.
In the building trades unions (in the US), the contracts generally spell out payment terms for “show-up time” of two hours paid at straight time rates for when workers show up (on time) for a scheduled day of work, which is cancelled before the start of work due to unforeseen conditions (normally weather, but it could be anything: failure of scheduled material to show up to be worked on, other contract work not yet ready, owner not ready for work to begin, etc.). That’s paid in the week’s normal paycheck as long as the worker shows up on time, and if he is prevented from working at the opening bell. If he picks up tools at his normal start time and begins any work, then the contracts state that he is due at least a half-day’s wage (again, straight time pay only). (This doesn’t apply if the employer decides at the end of “today”, for example that “we won’t be needing you tomorrow, so don’t come in to work”. Improved weather forecasting is saving employers a fair amount of money in this way now.)
It’s not a bad thing to have terms like this, and I like @hominid‘s attitude about it: If you make a demand on the employee to “show up on time and ready for work”, then it is only right to have conditions on you as the employer, too, to reward that in some way when you cancel. Plus it helps to ensure that the employee won’t decide on his own that “there’s not going to be any work for me today, so I might as well stay at home.” Weather forecasts aren’t 100% reliable!