In Germany it's 25 cents for plastic and aluminum. 8cents for glass.

A lot of people just throw the glass away in public bins, because a) glass is heavy and b) 8 cents is too little incentive.

The 25 cent cans most people return. If it was 1€ a glass bottle you bet your ass people would return them.

Typically metal is sorted out of every trash flow, it's really easy to detect and separate. Glass and metal are both 100% recyclable. If the incentive covers the cost of recycling / recovering the materials, it does not matter if people throw them away, they are just throwing away their own money.