Why would I bother with calling you lazy or irresponsible or inconsiderate? If you were someone I knew I just wouldn't invite you to stuff after the first few times you don't show up on time. Whether people don't mean to be inconsiderate when showing up late doesn't matter to me, it's still not respecting my time and I simply don't want to deal with that after a few times. But you are just a random person on the internet whose being on time or not does not affect me at all. But I don't actually believe that you cannot help it at all. Doesn't mean I'm going to argue about it, that's your cross to bear and has no effect on me.

The solution for you might be to have all/most social stuff at your place so you don't have to deal with getting somewhere at a specific time.