I've found it harder and harder to find powder dishwasher detergent in my country. I think they intentionally pull them off the market, I used to buy a large Finish container and now I can barely find a place that sells _any_ sort of dishwashing powder.
Yeah, in Poland two "premium"-ish brands stopped selling powder in favor of tablets, and the cheaper brand is often missing from shelves, I need to order it in delivery separately. Situation is funny, since salt and rinse liquid are still widely available along with supposedly 3-in-1 tablets :) . I guess they are not so 3-in-1 as the ads say. But I will continue buying powder for as long as it will be manufactured. It's cheaper and more efficient. Same with washing machine power.
Interesting, here in New Zealand every supermarket has at least one brand of powder. Normally Finish is one and competing brands includes locally made and/or eco-friendly ones. Hopefully that practice doesn't reach here!
I, too, went through like 18 months in the UK with the big stores not selling any until one reintroduced it recently. Alternatives on the internet were like 3+x the price, at least. It was incredibly frustrating. I now stock up and have 2-3 boxes of the stuff, in case it does vanish again.
Doubly frustrating since mine is a small, single-drawer dishwasher, so pods are even worse since I can't break them down. It leads to me having way too much detergent in the dishwasher and I end up with residue on the dishes.