Yes, I do have a wife and a 1 y/o. I also live in the Bay Area, CA where traffic is absolute hell and it isn't uncommon to drive an hour away to game. Which is why tardiness is not a concern to me.
I see it the opposite way - I travel nearly 2 hours to get to & from the game; add another hour if I had to dash home from work to get my DM stuff because the regular DM cancelled; game starts 7pm, game finishes 10pm - the pub kicks us out before 10.30pm and I have to be home by 11pm anyway or the wife likely gets antsy. I like chatting with the other players before & after, but any significant infringement on the scheduled gaming time is a big deal; if the game starts 1 hour late & I lose a third of the session I'm not a happy camper. One young player who's driven hard at work is sometimes late, but if so he always calls to let us know, so we can work around it, usually starting without him.
Travel delays - aim to be 15 minutes early, people forgive you if you're up to 15 minutes late; it has to be pretty bad to delay you more than 30 minutes at least in London.
But anyway, presumably your approach is fine for your group; it just wouldn't suit me at all. If I were in your group I'd be peeved by your being peeved that I thought my game time was precious, as well as being peeved by your lateness.
Edit: Re socialising, I've started coming to the game earlier (say 6.20pm for 7pm start) to get more socialising in beforehand with early arrivers. But game time is game time!
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