Yes, poor Mum would have been worried. And scary for you too no doubt. But you got through it and made your way home in the dark with your friends. Your mum could then stop worrying. You learned you could cope. You probably had a good story with your mates. You still remember it now. You have that narrative in your mind of how it all turned out fine, and that taught you something at the time.
If you'd had a phone yes your mum wouldn't have worried and you wouldn't have been scared or confused. But worry, being scared or confused doesn't actually harm us. It teaches us. Its how we are supposed to live. Next time a bus was late or didn't show you'd be better equipped to deal with the situation than you previously were.