The reality is, most of the time the materials do not get separated and the "eco-bottles" get sent to landfill. It is simply not efficient to have to remove the lids and composting does not generate revenue for waste management companies.
In my opinion, single-use PLA bottles with additional PET components should not be on the shelves in everyday shops, because we don't have composting available on a large-scale in the public arena yet. Nor do consumers have the tolerance to separate the pieces before sending them to either compost or recycling. Thrown in the recycling bin as a single item means they are contaminating our public waste streams which is not "eco-friendly" at all.
It is different at events where you have the ability to control the situation. Currently this is where PLA can be superior - it just takes work to do it properly.
The Warbirds over Wanaka event organisers needed to do more research before choosing to use PLA.
At the Summer Sunday festival, Charlie's water was used and all of the caps were painstakingly separated and sent to recycling, while the PLA went to composting. This is an example of how to be responsible for materials used at events and do it properly.
If materials can be composted then it is far more efficient and environmentally friendly than wrapping up PET bottles in shrink-wrap and sending them to Asia to be recycled.
But the reality is that until we have a system in place for PLA in the public waste stream, claiming that bottles of this nature are "eco-friendly" seems to be greenwash. I have been told that PLA does not break down in the ocean and releases methane in landfills - which is where most of them go.
If you want some of our abysmal statistics on recycling, you can find that here: Sam Judd: Plastic Addiction and the Myths of Recycling