Why do tropical hailstorms produce smaller hail than mid-latitude ones?

Answer: Growth zone is too shallow

Thunderstorms are weaker — Wrong. Tropical thunderstorms can be just as intense as mid-latitude ones, with strong updrafts and heavy rain. The difference is not storm strength but the vertical structure of the atmosphere.

Growth zone is too shallow ✓ — Correct! In the tropics, the freezing level is higher and the layer where hail can grow (between freezing and -20°C) is thinner. Hail embryos have less time and space to accumulate ice layers before falling into warm air, so they stay small. This is why even powerful tropical storms rarely produce large hail.

Hail melts before falling — Wrong. While some hail does melt before reaching the ground, that's a secondary effect. The main reason is that hail never grows large enough to survive the fall. If it grew big, it could reach the ground as hail even in warm conditions.