WHY should people reply immediately?
If you ask a reasonable timely question - are you coming for diner tonight - fair enough to expect a fairly quick reply. Otherwise, WHY?
I like the blue tick, it means my message has been seen, reply will come when it comes. If it's urgent, I do write URGENT and in upper case, and always receive a reply asap.
People can be checking their phone in a meeting, whilst waiting for an appointment, in the tube or train before being out of signal. Why does it matter if they reply straight away? It feels terribly needy.
I love modern technology. Yes, you have to be contactable much more often. But the positive far outweigh the negative: parents can keep in touch with children when abroad. I can work from home. I can go away for much longer because I can still deal with a few bits. I don't have to be stuck in an office the entire Sunday waiting for the one phone call from a foreign client anymore! I just live my life and answer my work phone when it rings. It's fantastic.
The beauty of text and any whatsap messages and the like is that you send them when it's convenient to you, and people read then reply when convenient for them.