“I need a break” should be a valid “excuse”. Again, the point if for your employees to get their work done, not literally glue their asses to their chair. Breaks actually help, especially on a nice day. In the office or remote, I take plenty of breaks to step out, talk a walk, get coffee, hit the gym, etc throughout the day. And the whole time people know where I am because my boss fosters a culture that embraces breaks so no one feels they need to hide it, and we post when we’re going to be away and change our statuses on our comms. It’s not uncommon at all on a ncie day for someone to post “great day, taking a walk, be back in half an hr or so”
and as for meetings and such that’s what calendar invites are for, if you start meetings just by rounding people up such that someone stepping away has a problem your forcing context switches and pissing off everyone, I promise
i also assume you must not work for a company with multiple offices, forgetting about the portions of the team I’m on that’s always been remote, or those like me that often worked remote at least once or twice/week even before the pandemic, we also have people on the team spread through 6 timezones, and coordinate with even more folks outside the team. Plenty of them work from the office, just a different one thousands of miles away. Keeping everyone in sync works the same way as remote employees.
Tldr everything you’ve listed in all your replies are problems that exist because of overbearing management and a paranoia that somehow your employees are pulling one over on you. Track your employees work, not their desk presence, and put in place processes to handle that and everyone will be much happier.