Don't always attribute it to pure malice. Just because you're addicted to your phone and will drop everything to type out a response to people, doesn't mean everyone lives that way.

Sometimes answering is not convenient and other times people just flat out miss messages. People who are with other people or engaged in something important can't always just drop everything to text you back. People who start responding to texts in the middle of conversations with other people are another kind of extremely rude. Consider what happens when you text someone and why it's ok to just sit there expecting them to drop everything they are doing to give you the answer they need. Try to visualize that idea of you hovering over them interrupting a conversation and demanding an answer. Are you that important? Now imagine that you're standing beside 5 others doing the same thing. Are you still that important?

There was a point when texting was so that you could have a conversation that didn't need quick responses. There are times where a 2 second glance at my phone when it vibrates is appropriate to make sure it's not an emergency. Beyond that I try to keep my focus on things, be it work or the people I am already out with. I feel less bad interrupting a conversation to answer a call, but less and less people will do that these days.

Other times I just miss texts, sometimes only seeing them at a time where it's really inappropriate to text back. I could be out at a movie theater, or out on a long bike ride. I could be at home where I just left my phone in the other room. Sometimes I try to follow up later and apologize but sometimes it just too late.

Texting culture is pretty weird, and depending on your age the number of people who live in one camp or the other fluctuates greatly. Some people are rapid fire on their phones texting constantly and other people try to stay off them. Instead of freaking out and getting upset that people don't answer you, try to just assume they are just busy or already at lunch/dinner.