But if you agree to meet people at a certain time, then being more than 10-15 minutes late without letting the person know is just rude, selfish and inconsiderate. Sure problems come up - these days there is zero excuse to not let the people know you are going to be late and give them an estimated ETA.
By being deliberately/incompetently late in those scenarios where you've agreed on a time, you're telling the person whose time you are wasting that you value your time more than you value theirs - i.e. that you consider yourself and your time as more important than them, and so fuck you - I'll get there when I want and you can wait for me since I am the most important one in this meeting and you and your time is worthless...
Are you late because you are just a bit disorganised? Please get a grip make an effort because you're a grown up and the people you are meeting had to make an effort to get there too.
Are you late because you are just an arsehole? Take a long look at yourself in the mirror.
tl;dr - depends on context.