Ask HN: Why is Apple's Messages' sync so messed up?

When I send a message on my iPhone and then look at the Messages app on my laptop, I usually see no updates for quite a while. This real-time push behavior has been around in Messenger, Whatsapp and other messaging apps for so long that I am just shocked that Apple is still struggling with it. And don't even get me started on using the search function. Is there something that makes this sync so much more difficult than in other apps?