If the Speed Queen cost 50% more, I would be inclined to buy it. But at 3x the price, I feel like it’s just easier for me to replace, and since it is Costco, I trust that the process will be easy.

Wouldn't that mean they should have longer stated warranty than estimated lifetime?

in other words, if BrandX had products they believed would last 40 years, they would have a warranty that says so, and it would not decrease the reliability 1 iota

Also, longer warranties can be a selling point (speed queen does this with the same exact internals being sold with a higher warranty on the 'fancier' ones which just add some more features to the board).

And, a company has to hold monies on the books for warranty service, so a defined warranty period that is not unreasonable can help with that.

But the "best" company in a given market only needs to warranty beyond the nearest competitor.

Speed Queen also is implicitly dealing with people who would buy the "lifetime" warranty residential unit and run it in a commercial setting, where the wear parts would wear out.