As a ref I'm delighted to see this. It's my biggest pet hate, you call the teams in and the coaching staff and 11 players just ignore you*. As a single individual there is nothing you can do, you can go mental and start without them but that would cause a riot. I'm not sure PL referee teams have any more power, they knock on the door and ask the players to come out, if they ignore him or refuse, what can he actually do? Probably has 2 burly security guards in his personal space as well. Be interesting to see the decisions City got or didn't get in the first 10 minutes of the second half of these games. The only power the ref has his is whistle once the game starts, it's my go to weapon in these scenarios.
The last league match included here is also the longest delay. A game to win the league and the best manager in the world has nearly 3 minutes longer with his players than allowed. That's an advantage that a £100k fine doesn't come near covering.
* I assume the clocks starts at this point and each team is on their own time.