When this started in France the supermarkets simply removed all bags except for the really expensive large one's. They kept a very small stock behind the till and charged for them. I've never even been interested in how much they cost.
Granted we can't keep filling the planet up with these plastic bags, but there has to be a compromise. I was constantly getting caught out in France where I had walked to a shop without a bag and without a car. They had no bags except the expensive one's and I had not choice. So I have a collection of expensive bags now because they're so large I can't always be carrying one. I now have one in my man bag and one in my rucksack for my computer on the basis that if I go to the shops (I have no car here) and need more than one bag, I'll have to buy another one.
The reusable bags are made differently, are more biodegradable and I do use them more than once. But it is not a problem with an easy solution.
I just pay the money. The best bags I have are Swiss. Some of those are 5 years old and are still well used. They have double handles on them, both to hold in your hand and to put over your shoulder. Although those are becoming very hard to find now... Put simply, I'm never going to take a shopping basket to work on the off chance I'm going to do some shopping. I can just see me taking it to the pub after work.....
As for the cross contamination? I don't even bother. I've never been made ill by anything I bought recently in the shops, I usually cook most things to destruction, I'm not an Al Dente person...