Why can't I get a dealer to answer my messages?

Most dealers operate on the system that if you're interested you'll either call or come to them yourself. They don't want to spend a lot of time on calling people with little chance of a sale.

Are you talking about new cars or used cars? A new car salesman at a dealership will usually call until you can't get rid of him/her- those are big sales- I'm guessing you are talking about used cars- and a used car salesman is a whole different breed

True, new car salesmen are like ticks, can't get rid of them until you buy the most expensive car on the lot with full options. Used car salesmen don't want to waste time on maybes when they can be hounding someone on their lot instead.