To your #3 - in my (US) city there have always been those cheap goods stores. There was one in the (2000 person) town I grew up in, too. The big change I'm seeing is that the independent, mom-and-pop ones are being displaced by major chains.

> 1. We have more people without much disposable income

In absolute terms, or just on average? This may be the case simply because the US population went from 250 to 320 million people over that time, but household disposal income is up considerably as well.

An alternative answer may be that Dollar stores have very low franchise fees (~$50K, from one site I looked at) and low inventory costs. This, along with cheap commercial rent, makes it an attractive option for non-tech people who want to start a retail business but don't have a lot of money saved up.

> Save up and buy something that will last.

Unfortunately, just because somethings costs more doesn’t mean it will last more. Maybe in the past there were brands that prides themselves on durability, but now most of the stuff seems not to really consider durability and longevity, and the financially smart move might just be to buy the cheapest thing that works and plan on replacing it when it breaks.

There is something to that. But consider household tools like Craftsman (had lifetime warranty). Now Craftsman is cheaply made with poor metallurgy and has a limited warranty. People will buy that at the HomeDepot. Sure, you can buy more reliable brands, but most people like you say won't know which ones to buy since many have been shipped overseas.

Furniture is now disposable. Clothing is disposable (even if you didn't mind fashion, it will end tattered after a couple of seasons. You can still buy excellent clothing, it just costs 5x.

This isn't new and your example is a good one. Craftsman tools have always been cheaply made with poor metallurgy. They got by with the lifetime warranty because they marketed themselves at consumers who don't rely on their tools and don't use them very often. At least as far back as the 1950s and 1960s, people whose job depended on their tools wouldn't touch Craftsman.

iphones are pretty expensive and those go in landfills too

Same as 2008. a lot of ppl left behind in recovery, which benefits Walmart and dollar stores.