Hammockbunny and others, here are some ideas I have for some of plastic trash problems in Bali and elsewhere. Some things I will do and others can as well.
1. Buy a set of 30 pyrex drinking straws with the brush cleaner. Donate the set to a local warung popular with tourists. Tell them tourists take notice of eco-friendly businesses and will frequent their warung if they use reusable pyrex straws. After other warungs take note of this they will get them too. Hopefully. Also tell massage places to stop giving out the small water drinking boxes with the plastic straw. Some places give you a glass of water or ginger tea. That's better. These pyrex straws can be bought online or buy the tubing and cut, sand them yourself. It's a day project. Could be a school or family project.
2. Tell Circle-K AM/PM, Mini-Mart a boycott will be started and tourists will only shop from the chain which sells wicker baskets or offers biodegradable plastic bags to customers. Or has plastic hand baskets customers get for free but can return to any convenience store. Or make customers pay 10,000 Rp deposit for a plastic hand basket which is then reimbursed when the basket is returned. Just like shopping carts in Europe often require a 1 Euro coin to use which is then reimbursed.
3. Before coming to Bali on holiday buy a roll of small biodegradable plastic bags use for dog crap and give to vendors. That idea has already come up.
These ideas can be applied all over the world and not just in tourist areas.