Companies have gotten extremely used to having people on the electronic leash. Not just IT folks (though this is a large part of the population in question), but anyone whose job has been defined such that they need to be reachable within 30 seconds. I'll pick on IT folks just because so many people think of them as the type who have to jump the instant the cell phone rings.
Consider a typical IT team. At some point during the morning, they're all on the road to make it in to the office for the start of the business day. And at some point in the evening, they're all on the road heading home. During those times, none of them would be legally able to answer a call. Before someone says "well, pull off the road or go find a parking space", I'll speak for my own commute and say that there are long stretches of it where there is no shoulder to pull off onto, and when you only have 30 seconds to answer the phone before it kicks to voice mail, getting to a side street or gas station or whatever where you can park isn't often possible.
So what would the company do? Have the staff work staggered shifts so that there's always someone who is either at home or in the office during commute times, and could therefore legally answer the phone? Allow telework for part of the day so that commute times could be staggered without forcing people to adjust their whole day? That second one works fine for the morning, but it wouldn't help for the evening commute, or vice versa. Have a designated telework day for each staffer to keep them off the road? And so on. All decent ideas, but the current climate of "this is our business day and it's when you are to be at your desk" wouldn't want to embrace them.