Tennis is the only sport where the players spend half an hour warming up against each other before they start the match.
The tennis warm-up is the most pointless waste of time in sport and should be scrapped straight away. They have practice courts. That's where they should be warming up. They have trainers and physios to take them through a stretching routine in te dressing room. So the warm up serves no purpose except to delay the start of the contest and make it even harder to complete the match if there's any risk of rain interrupting.
In every other sport it's part of the game to get used to conditions at the start of the match. Can you imagine if cricketers bowled half an hour of warm up deliveries at the opposition batsmen at the start of every day?
Being ready from the word go is part of sport and tennis players should learn to deal with that.