Who I have the same questioned this topic

I have the Note20 and use Verizon Message+ for texting. One of my friends also has Verizon and uses Message+ for texting. Everything always shows as Delivered, however some of the voice recordings I send sometimes show as Read while others say Delivered, even though the recipient did listen to the voice recording. I don't know if they have read receipts turned on, but I'm assuming they do since certain voice recordings do show as Read. How come not all voice recordings show as Read though? How come some only say Delivered? And how come not everything says Read since some things do? Anyone else have this glitch?