Externalizing these is so much cheaper to the companies involved that they do it that way. Setting up a bottle recycling plant is expensive, and that cost is not passed on to the consumer but absorbed by the company. So the profits go down.
The bigger question you should be asking is why haven't all developed countries adopted such obviously sensible policies. I have a sneaking suspicion that the reason is regulatory capture.
If that's the case why not take the time to look into the regions in the developed world that have implemented these systems and see how they work?
Someone else in the thread mentioned that the province of Ontario (which IIRC is the largest purchaser of alcohol in the world) has switched over to a system homogeneous bottles that are washed and reused.
If a region as vast as Ontario with a population of approximately 14 million can do this, why isn't it feasible else where?
Sure. But you say that as if it's easy. In some cases it's not trivial to put a monetary figure on these things. This may be why they are an externality in the first place.
More importantly, in each case where you intend to make someone pay for something they are used to getting for free, they will resist that change, even if that something is the right to pollute the river.
Making externalities part of the cost has always been a struggle. Nevertheless, I agree in principle.
If not for that problem, we could simply charge garbage collection by weight, including all costs of recycling and/or disposal, and let the market sort it out.
I'd like to establish a variant of Chesterton's fence - something like 'You don't get to get morally outraged about something without understanding "why".'
Why are developed countries not doing it? My guess would be cost, so why is a "wasteful" practice cheaper? Is it something else than externalities that aren't properly represented in the cost, or is the morally odious thing possibly more efficient, or is it something else?
Without that answer, it's hard to suggest meaningful action: If it's the externalities, we need to make them part of the cost. If it's actually more efficient this way, we need to stop demanding to make it worse. And if it's something else, then we need to figure out what it is and whether/how to address it.
But right now, it seems like random things are picked based on looks/feelings, pointed at, and demanded to change (usually to something that was done in the past and is no longer done).