Most people put plastic shopping bags in the cupboard in the home, which is silly. Why not change that habit and ALWAYS put them in your car’s boot, then they are always available when you need them.
And if you forget to get them out of the car as you go into the supermarket that is not a problem. Simply do not get any new bags from the supermarket, and put all the shopping back in your trolley without any bags. Then fill your bags at the boot. Ok not so good on a rainy/cold day perhaps, but if you start now then you will get into the right habits come Autumn time.
Oh, and by the way another benefit is that no-one wants a boot full of shopping bags. So naturally you will not want to get yet another six bags just to leave enough room for your shopping!
Food from supermarkets often comes in plastic boxes. As these head for recycling they take a lot of space up in your recycling bin. If you snip the corners with a pair of scissors then they collapse ever so easily. Remember – wash then snip then recycle.