Legal definitions vary country to country: I wouldn't be so quick to insist on some universal definition. I'm pretty sure you're wrong about US law there - docking someone's pay for "chatting" sounds extremely difficult to defend.
Besides, multi-tasking exists: sometimes I need to let my brain idle on another topic for 15 minutes, because I'm working through something complex, or just wrapped up a project and have a meeting.
Certainly, nowhere I've ever worked has tried enforcing anything like this. I've had plenty of co-workers who made a point of wandering over to socialize for 5-10 minutes every day, which must have easily added up to an hour a day - but they were also the expert that knew exactly where everyone was and who needed to coordinate with who.
I’m not in the US, so that may be right. In my view this is more about how the employee feels about it: I don’t want to get into a dispute whether the half hour a day I spent on the rambling channel counts as work or not. For that it makes a significant difference if people use the channel to discuss their hobbies or whether they discuss work-related ideas. I also don’t want to miss the work-related topics just because I’m not interested in the hobby discussions.
Besides, multi-tasking exists: sometimes I need to let my brain idle on another topic for 15 minutes, because I'm working through something complex, or just wrapped up a project and have a meeting.
Certainly, nowhere I've ever worked has tried enforcing anything like this. I've had plenty of co-workers who made a point of wandering over to socialize for 5-10 minutes every day, which must have easily added up to an hour a day - but they were also the expert that knew exactly where everyone was and who needed to coordinate with who.