The starting first edge can be shown mathematically, as long as it is true that serving gives you an edge.
Call p the probability that the serving team wins any given game. In pro padel this is roughly 0.6, or more.
The first server serves games 1, 3, 5, 7, 9, 11 and the second server gets 2, 4, 6, 8, 10, 12. If the set ends after an odd number of total games (6-1, 6-3, 6-5), the first server has played one extra service game. If it ends after an even number (6-0, 6-2, 6-4), they've served equally.
That one extra service game is the whole thing. It's one additional coin flip weighted at 60% in your favor.
You can verify this exactly. Model the set as a Markov chain on (your games, their games) with transitions based on who's serving.
omg thats crazy, thanks so much this makes sense, think Ill start serving from now on lol, thanks
6-5 isn't winning, that scenario would be 7-5, but that's even.