Half marks here for getting half of the answer right

But it is still only half marks for while they've managed to get the incentives correct they've missed whether we should be doing the activity at all:

Ministers are considering plans for a plastic bottle tax as part of a crackdown on waste clogging up landfill sites and entering the sea.

Customers could be forced to pay an extra 10p or 20p for every plastic bottle or container they buy, which they would be able to reclaim if they return it as part of a deposit return scheme.

If you are going to try to incentivise then yes, money is the way to do it. Quite apart from anything else every schoolboy in the country looking for some extra pocket money will be scouring the hedgerows looking for some to hand in.

But this still leaves that much more important question unanswered - should we be recycling plastic bottles at all?

Think back to the days of glass ones, when we did have a deposit scheme and returns? Why did we stop doing that? Because making new plastic bottles and throwing them away after one use costs less that collecting up all the glass ones and using them again. We also know that recycling plastic bottles makes a loss (very definitely when including those collection costs) and that thus we expend more resources doing this than just the one time use would cost us.

Finally, we don't even have the knowledge that the population desires that the recycling happen. If that were true then it would not be necessary to institute a deposit scheme in order to increase the recycling rate, would it? 

People don't want to do this, it costs us all money and resources to do it and aren't those rather more important points than having finally stumbled across the correct way to force people to do it?