Here, teams don't hire the umpires, our association does.
For me, I do games at my association. They charge teams a set fee to play X amount of games (12?) per season and then the association budgets the umpires for those games. The lower age Rec level games get a rookie umpire and a senior / training umpire. The older / upper level travel teams get the experienced, more senior umpires. You certainly wouldn't want to put a rookie on a travel ball game and the senior umpires typically don't want to do 9 and 10u Rec ball games. Yes, you will have senior umpires that might be questionable as far as quality, but still better than throwing a 14u rooking in there.
We've found that having the rookies team up with a "training" umpire goes a long way in helping the new guys to learn AND come back the next year.