What I like to play and what I get to play are usually different. Within a year of a new edition, I'm usually sick of low levels (1-5) because I have terrible luck with groups that fizzle, break up, move away, etc. So as DM, I often start at mid- or even high-level.
As a player, finding a DM willing to start after 1st level is like winning the lotto. It's happened to me maybe 2-3 times ever.