DuckDuckGo is a company, so it's aim is not develop something to solve a problem they have but making money. That's why it can't be trusted as any other proprietary service.

Only FOSS so projects developed by someone, companies included, with the aim of solving some authors problem or desire can be trusted to a certain extent.

The rest it doesn't count much you may have "ugly dictators" or "less oppressive dictators" but they are still dictators. It's their nature, no matter how good intentions they have at start or they try to keep.