The coins are in the coin compartment, etc. The liquid system would work well for toys. The purpose is to bring out something new, surprising and interesting. The liquid system would not work well for a purse. When you want money, there's no use pulling out a pair of sunglasses, and vice versa.
Some people have liquid-system purses.
It works, but not well. The solid system would not work well for toys. When you ask for a toy, you would always get the same one. Give me another. You would then always get the same second choice, etc.