Is it maybe a refrigeration issue? You're subconsciously putting off sticking the dairy in your basket because of a paranoid fear that somehow an extra 10 minutes outside the refrigerated cabinet while you complete your shop will cause it to go off and give the whole family a nasty case of stomach cramps. Or actual death.

So by the time you get all the rest of the groceries you've forgotten and bypassed the dairy and have no visual prompts to remind you.

You could get up a petition to have the store manager relocate the dairy section to right by the checkout.

Maybe with flashing signs saying something like 'Don't go yet - get yo' yoghurt!'.

Or take one of those silvery, quilted NASA-style refrigerated produce bags in with you, and head direct to dairy upon entry. But would you get taken out by store security snipers if you slipped your cream into an unauthorised receptacle?