Here: Prajongjai is admonished by the umpire for holding up a hand to delay the server. Players do this all the time and aren't pulled up about it. Have the umpires been to told to clamp down on this?
Yes, it's been more strict for couple of years already. Receiver must be ready when server is, otherwise they delay game.
Holding up the hand is not a problem, and in itself does not constitute undue delay. But doing it after a long wait (in this case they even swapped shuttles beforehand!) does. That's why the umpire correctly intervened. There are no fixed rules for undue delay; it is the subjective opinion of the umpire that counts. The umpire will consider, among others: Is this a one-time affair? A single delay is not nearly as much as a problem as if the player is consistently delaying. Is there a reason for the delay? If a player's laces open up once, that's fine. If both players play a 100-shot rally, the umpire may even invite them to towel down. Here, the match has just started, so there is no reason. Does one of the sides consistently delay more than the other? It is normal for different matches having different rhythms. For example, low-level junior players will often have the shuttle in their air once you've finished the score announcement, and you'd consider the normal rhythm at high international levels delaying already. Umpires have been told to reduce delays for years if not decades. I wasn't at the briefing for the Spain Masters, but I would be surprised if there was a specific push there.
From my experience, No. The reason is that the leadership, from the referee, is neither clear, nor consistent, or strong. If it was, then these situations would have been nipped in the bud, as the expression is. Check this incident, from Korea Masters 2018 - http://bit.ly/2PirgY7