Sure, it's "voluntary" in the sense that if you don't do it, you won't be picked up by any major distributors. How many non-Energy-Star appliances do you see at Home Depot and Wal Mart?
(Edit: also, federal procurement requires certification. So you know...if you don't ever want to sell to the government, go ahead and ignore the certification.)
It’s a bit like making a Department of Deliciousness, and “voluntarily” labeling every cookie sold as part of the SweetStar program. My goodness…people like certified delicious products! Let’s hire more people…
I just did a search for dishwashers on Home Depot's site.
166 dishwashers are Energy Star certified out of 310.
Of standard-size only dishwashers, 136 out of 241 carry the Energy Star certification.
That's a not insignificant portion of the dishwasher market that has not done this thing that you put in scare-quotes as "voluntary" and are still carried at the number two reseller of major appliances in the US. Walmart is not a significant reseller of dishwashers.
At Lowes (the number one reseller), 396 out of 539 built-in dishwashers carried the Energy Star certification.
But now you’re describing market forces.
I shop at lowes, not home depot or walmart, but lots.
Look at all the fridges lowes sells: https://www.lowes.com/pl/refrigerators/4294857973?goToProdLi...
There's 994 total, 554 are energy star certified. Just over half.
To take it even further, if I shop only what's in stock at my local store, there are 17 options. 11 Energy Star certified.
There's no absence of options if you don't care about energy star certifications.
If you want to be certified, sure, but that's voluntary.
The only thing energy star is going is mandating companies inform their customer so the customer can decide and compare products. The free market is making you dishwashers use less energy, not energy star