Why would youth coaches play zone? They want to win (winning over teaching) as their first priority. Zones exploit young players who cannot shoot and help limit 'better' players as well as pick-and-roll. They probably aren't using zones to protect players from foul trouble.
Teach players that zones have limitations:
1) they don't stop transition offense
2) they allow the offense to decide where and whom to attack
3) they have no assigned rebounding so it may help offensive rebounding
4) each zone has particular weak spots
There are predictable advantages to exploit, using the 2-3 as an example.
Figure 1.
1) basic principles of space, cut, pass, and screen still apply
Figure 2.
Proper spacing yields better passing angles (Figure 2) and extends the zone.
2) offensive players "behind" the zone are invisible (Figure 1)
3) make two players guard one (Figure 1)
4) scoring percentages correlate with PAINT TOUCHES and BALL REVERSAL
5) look to deform the zone (shot fakes deform north-south, pass fakes deform east-west)...
6) players also need to learn to "look off" defenders who are reading their eyes.
7) don't let the ball stick - "2 second rule"...one potato, two potato.
I like to use the acronym "DR FlaPS"
1) Dribble into gaps (penetrate to pass) to make TWO cover ONE
2) Reverse the ball (11-12 year-olds often have trouble with skip passes)
3) FLAsh (cut to open spaces)
4) Post-up (if you have the personnel)
5) Screen
The dribble can open the middle.
Screens have a myriad of potential uses, compromising the top of the zone or the bottom.
I have delayed introducing zone offense at the earlier ages. I think this is a mistake because general principles still apply, just attacking different defenses.