'Biodegradable plastic' is great I'm sure but it promotes bizarre thinking like this. How about we just decide not to have mass-pollution parties for no reason, rather than trying to reduce their impact with expensive new materials?

Because changing human behavior on a large enough scale is often orders more difficult than finding a technological alternative.

Of course in the long run you're right, but where traditions are involved, sometimes it can ease the transition. "No balloons" is a much harder sell than "expensive biodegradable balloons", for someone who feels it's an essential thing. Eventually price pressure will cause the tradition to phase out organically, with people feeling like they have a choice, rather than the resentment caused by "no more balloon release parties, starting next week!"

Is this really that much of a thing? Presumably we're mostly dealing with groups - probably mostly charities. Is it really so hard to create public consciousness that releasing a tonne of baloons into the air for no reason is littering that putting loads of effort into designing and promoting alternatives is worth it?

price pressure like a fine or a hefty surcharge at the point of sale would help too, no?