Read Receipt feature is one of the best things about iPhones.
I prefer my clients, friends, family etc to have iPhones for the transparency of knowing they’ve read my message. When I meet anyone new, including a client, and they have read receipts turned off, I immediately ask for them to turn them on.
Having read receipts on teaches & trains accountability (to oneself) to be respectful and answer in a timely manner.
Personally, I always have my read receipts kept on as standard for everyone.
JTtorretto's post in iMessages-Read Receipts not turned on was marked as the answer