Giving you 'seen', then answering later, to some questions or making plans that takes up to few seconds to respond?

We are all from 'self improvement' side, and it looks so lame and dumb to do such a thing.

We are good friends, talking about 3/4 of us, going out every weekend, but usually it makes me angry and avoidant to send text sometimes because it takes so much time to respond to your text for no reason that makes sense

I made call on it few times, it's always 'i was busy' or something, but it sounds like they want to appear busy and not really deep into job

I know they saw when the message comes but appear to text later, sometimes they would just 'seen' and respond later.

Do you do this, and if so, why? What do you think of this?

edit; just to add. We are good friends, hanging out, making plans, giving me ride home, paying rounds, talking about important stuff and sharing, taking care off, everything is good, but, on other side this stuff is bothering me and poking my left eye everytime, it just turns me off and makes me resent them