I have considerable sympathy for you, especially since my mother has chronic back pain and similar shopping trips can be a nightmare on her bad days. However, I think there is considerable room for win-win on these things.
Just consider the trip to the Wal-Mart. I haven't lived in North America for a long time, but in my recent trip to Canada to visit my parents, we went to Wal-Mart. Look at those sprawling mall complexes with their massive parking lots. We had to drive from parking lot to parking lot, just to visit another store!
And the Wal-Mart itself was this behemoth structure with football field after football field of space under its roof. I mean it's half a kilometer from the frozen pizza to the checkout line. If you can't walk 200 meters, you can't shop in Wal-Mart without using their motorised carts (which are admittedly very cool).
Imagine a completely different situation (one which I thankfully live in every day). Imagine that you had stores that were close to where you lived. So close, in fact, that you could walk there if you were abled bodied. But if you were not, you could take an electric bicycle (which many elderly people use where I live) or even an electric cart similar to the one that you can find at Wal-Mart (these are really rare where I live -- most people are quite happy with their electric bicycles, but I've seen them frequently in the UK where I used to live).
Imagine that instead of several square kilometers of parking lots to contend with, you had hundreds of small shops. You had butchers that are just big enough to house the meat it sells. You go up to a counter, which is less than 10 feet from the door and you get your meat and -- lo and behold! There's the cash register, not 3 feet from where you are standing.
I could go on, but the biggest thing that makes this hard for people in North America to imagine is that it is so different. The lifestyle is completely different. Instead of going once a week or once a month to some massive discount store and buying a van full of goods, you go every other day and buy enough to fit in a basket on your bike. It seems like a lot of time, but instead of driving for 30 minutes to the store and spending 20 minutes fining a parking space, you walk 5 or 10 minutes to the store. That's what it means to build cities that are good for walking.
I write this with the full knowledge that my words are not good enough to explain this concept. Even my parents don't understand. When I stayed with them, I discovered that there was a shopping centre only a 20 minute walk from their house. I started walking there to pick up small things for dinner every day (hey 40 minutes of walking a day is not bad). They thought I was insane. Why would you walk to the store when you can drive? Why would you spend 40 minutes when you could send 10? They couldn't understand that the walk was the point.
And so, while it is unreasonable to expect North America to become Asia or Europe suddenly, I think there is a lot of things that can be done to improve the situation dramatically -- like rezoning areas so that shops can be build where people live. Things like mandating that parking lots have pedestrian paths that allow you to walk to the store without being driven over by a mini van. Things like having down town cores which are already mixed use to have walking only areas. Things like building safe public transit. Things like not approving large box malls in the middle of nowhere surrounded by seas of parking lots and no access to public transit.