Ja, ja, all this is good and fine/ Only if the umpire recognises these sort of situations. Pattern recognition is a fundamental aspect of umpire preparation – the same way that the first responders, end the ER-personnel, prepare.
You mention, the receiver has a pattern of not being ready. What is this? Two points? Three points? When does it make a pattern? Three data points for me is adequate to draw a trend-line. How many for you?
Umpire never threatens with cards. Cards are disciplinary devices to help control game-matchflow and player behaviour, they are in my book at least.
If the receiver has a pattern of not being ready, the umpire will likely tell them to hurry (the vocabulary mentions Get readier quicker).
If the server served intentionally while the receiver was not ready, the umpire can also tell the server Don’t serve before the receiver is ready.
This same exact situation happened at the XDSF (INA-ENG) at the AE2020.
The outcome was that the INA team was awarded a yellow card.
I will tell you, what Banham (llok him up), should have told that umpire – smile to the INA male player, nod, and let him serve, again. This would have been acceptable to all players on court.
Why? I hear you ask.
The player who served is doing nothing wrong. He, is effect, doing exactly, what you told him. He followed your instructions.
The player in White (female, English team) was setting the situation up. This happened at scoreline of 13-12. She was practically never ready as soon as she took ready position. She adjusted, while the opponent was waiting for her to get ready.
See the video clip again to figure this out.