Bag Boy

Yesterday I was observing a gaggle of women out with their toddlers. Each had a stroller and a bag big enough to hike the Appalachian trail. I'm not sure if it's just because I'm a guy, but I don't get it.
I'll excuse the strollers for now and rant about them later, for now let me focus on diaper bags.
If you have a child in diapers, you do need some way to carry spares. Babies are notoriously unpredictable and some things can't wait. It's just not cool to let your baby wallow in their own filth when out in public. You need to fix that. What I don't get is carrying enough supplies to outfit a baby expedition for a week. You're out for what, an hour, two? Even if you're out all day, breakfast to dinner, you're just not going to go through that many diapers. Think about a day a home, if you don't go through 30 diapers in a whole day, they you certainly don't need to carry that many on a trip to the store. In fact, I'd argue that you don't need to carry your diaper bag into the store at all. Leave it in the car. After the first month of parenting that's what I did.
A typical trip to the store (if you're a guy) has you inside the building for 30 minutes, tops. In that time anything can happen, but as a parent you usually have a pretty good idea whether the flood gates have recently opened or if you're awaiting an avalanche of stink. If you have a pretty good idea that you're in the clear, leave the bag in the car. 99 times out of 100 you won't need it. The quality of your life will improve dramatically.
Unless I was far enough away from the car that a trip back would be a pain, like at a baseball game for instance, I never brought a diaper bag in anywhere. I always said that if things got that bad, I was abandoning the expedition and heading back to the car for supplies. It drove my wife crazy but eventually she saw where I was coming from. I don't think it's that men don't like carrying giant purses full of baby supplies, we just don't think they're necessary in the same way that women do. If I can tuck a diaper and four wipes in my back pocket, I'm ready for most anything that is going to happen between now and when I need to feed the baby next.
Of course that's the hole in my theory. Our babies were breastfed. So I either had my wife with me or the watch was ticking between when I left home and the time I had to get back to the freezer and bottle warmer. I didn't need to pack for an expedition because I never went on one. My trips out with little babies were more like astronaut missions outside the ship. Breast milk is just too precious when you have to rely on another person's boobs for it. The supplies I needed for the survival of my crew just couldn't be practically transported. I'm betting that bathroom facilities in a space suit have some correlation with the lack of food available. And maybe that's it, maybe mothers need more because they have the potential that a short trip could lead to an expedition. If you're carrying an automatically replenishing supply of food on your chest, then the world is a different place. Maybe those moms I saw were heading from the park on an epic journey and I just didn't realize it.
I doubt it though, I think they just like carrying a huge purse.