El Salvador has a variety of ways of getting around. The intercity buses seem to be independent contractors who buy used school buses, possibly from the US, and customize them. They are interesting. There is a turnstile at the front. Pay your money and pass. A helper is at the back to handle people wanting to disembark. His communication with the driver involves a lot of yelling and whistling.
An alternative to a bus are these trucks you see with a flat bed and a metal frame. There is no sitting down but I actually think you are more secure at times than the bus. We rode this one down from the top of the San Salvador Volcano.
Then there is good old fashioned travel in pick-up trucks. I stopped doing it in college and it fell out of fashion in the US after some highly publicized accidents in which people were thrown. I did ride in the back of one with a cap, which I also think may be safer than the buses. Some people ride in uncovered pick-up trucks for both business and pleasure.
Private cars run the gamut here. Some would not pass state inspection back home for a variety of reasons. Even nice, older vehicles have some flaw with a door catch or window. It is the type of thing requiring a special part from the dealer but costs $120 for a new door handle.