Primarily, there has been an extraction of excess profit on consumer goods rather than investment in more efficient production or better products. I have suspicions that this is because of the relative ease of growing a profitable (but easily copied) manufacturing business out of China over the last 20 years, but it really doesn't matter why.
The other example of this is Oil Majors who have very little incentive to invest in new oil production or refining (even though it may be needed for the next decade), and instead take all excess profits to pay out as stock buybacks or dividends. They are in the profit taking stage of the business not the growth and investment stage.
Having the external hard rubber last longer than that is just unnecessary weight.
You may just be in better shape than you were in college. Distance stacks up fast and running faster wears shoes out faster.
sauce: I run marathons and go through about 6 pairs of running shoes per year
This is probably not the best for my feet, but when I bust a hole where my big toe goes I feel less bad because I spent $10 and not $100.
Skechers is building a sprawling set of office buildings in the expensive town of Manhattan Beach, CA. That money has to come from somewhere.
And shoes are an odd one. They have never lasted a long time. Ever. Only shoes that will last, are the ones you don't use often. You can kind of make this work with a rotation of shoes. Having recovery between wearing helps. They are still very much a consumable.
Shoes: I can't tell which brands are which anymore and it certainly looks like they're all made in one factory. I can't find a pair of comfortable day-to-day walking shoes. I have to make the best of what's available which means dealing with the discomfort and pain through trial and error.
For shoes, I don't know what to tell you. They have always been consumable. And often uncomfortable. Such that I honestly think the catch is we get more sensitive as we get older. Certainly moving more weight.
Shoes: A month ago I tried on ten pairs of shoes by six or so brands and felt little difference among them. The only difference was price: ~$60 low end, $130 high end. And these were nothing fancy, just shoes intended for daily use by non-athletes. None were good but I had to pick since my current pair were in tatters. I went with the $60 pair and am futzing with different insoles to get something usable. Maybe there is a magic $300 pair that will do the job.
Four miles is clearly me making up a rough number. My assertion is more that many of us do not have great walking posture or ergonomics. Note I am not saying it is our fault, per se. Just that walking and techniques that lead to long term comfort are surprisingly ignored by most of us. And this has far more impact on things than your shoes will.
Related questions, can you still squat with flat feet? Do you keep your back straight when picking up things? Not just lifting heavy things. When picking a dropped pen off the floor, what do you do?
And obviously, it could very well be in your specific case it is the quality of shoe. I've seen a surprising number of folks where it just isn't. :(
The bad experience with shoes has remained constant the past 10+ years through periods of good conditioning and not so good conditioning. I think my ergonomics are pretty good adjusting for age.
Unfortunately I can't go back and remeasure material and construction quality from years gone by. My perception is that the shoe uppers are now all stiffer and less flexible than years gone by and the the sole materials are hard and have no give. I've gone to multiple shoe stores looking but have come up empty.
Whatever they're not spending on their shoes, they're not spending the money on building design either since the buildings aren't much to look at.
Bought a pair of running shoes from Skechers early last year, had to throw away this year because the soles got worn out and I kept getting injured on one foot because I was stepping unevenly.
I bought Skechers because I had once had a pair of sneakers that lasted me the entire 5y of college. No such luck now.
No reason, just greed.