Hmm, a little guilty of that, yes. Although I've definitely been late for work, missed trains, come close to missing planes.
There is a reason for it I can recognise in hindsight.
Work - is a routine, it stays the same every day. Therefore you work out the plan, you stick to it, as long as you do the same thing every time you can't go wrong.
Big train/plane journeys are infrequent, one-off events. There's usually some other transport involved since you don't always drive there so you need to work out timing quite carefully. With a plane there is also leeway as you know you need to be at the airport 2 hours before to deal with security, check in, etc. Perhaps with trains too, e.g. if you're planning to pick up tickets at the station.
Meeting with friends is neither a big journey/event, nor a routine. You tend to meet them fairly locally, meaning that you think you have an idea of how long it takes to get there. That would mean that I wouldn't typically think to plan this out to the degree that I would a long, important journey.
What I've learned of course is that I have to apply that level of planning for the big important journey to every little thing. When I do this, it works fine. The problem is that I have to prompt myself to remember to do that, it's not an automatic assumption, and sometimes I forget or fall back onto my "Oh it takes 20 minutes to get to