A couple of points here - no most shops do not put the receipt in the bag - they put the receipt in your hand and bung your change on top like some crazy balancing act.
It's a good habit to 'file' your receipts in your purse or wallet til you get home. At Xmas gather all gift receipts in an envelope and put in a safe, and memorable place.
And as for T K Maxx. Was a favourite of mine til they wanted 20p for a carrier to protect a big lampshade from the rain. Served at customer service cos not one till in the whole shop, 2 floors, was manned. Refused to budge til I got a free bag.........and they say it is all to help the environment. Their own website says they have cut back 50% on bags so they are saving a bit as well ......