Because it's hard to make non-shitty products and be known for it.

By the time you have a reputation for quality products, you're often acquired or out of business. There are actually cases of this in some specialty equipment.

Because everyone buys your product once and never thinks about it again.

Really: I’ve talked to commercial product managers who bemoan the fact that all their customers are perfectly happy with the 10-20 year old instrument they have. There’s no revenue there.

Established companies will use their massive advertising budget to shit all over your product and get exclusivity contracts which make it very difficult for you to spread because you spent your money on engineering. Your repeat customers will be decades away and surviving decades until that point is difficult. You could offer good repair and part replacement services to help but that has a lot of overhead and organizational costs itself.

Because how can you tell apart a brand that makes durable appliances from a brand that merely claims to make durable appliances? Not to mention that any money you invest in making durable appliances will give you better short-term results if you just dump it in some advertising & marketing, and short-term results are all that the current "system" rewards.

People get what they pay for. If you want industrial-strength stuff, you have to pay, a lot. People also forget or don't know how expensive things were back then.