Not because they are lazy. Because checking is slow and dull, and because an idea feels better before you look.
You think of something on a Sunday. It sits with you for a week. You tell one person and they say it sounds good. By the time it occurs to you to find out whether somebody already built it, you are attached to it, and the search you do is the one that confirms what you hope.
Then six months later you find the company that has been doing it since 2023, with funding, and you wonder how you missed them. You did not miss them. You did not look properly, because looking properly is two hours of tedium and the answer is usually disappointing.
Where this came from
Prior was built after an evening spent checking seven business ideas by hand. Each one seemed reasonable. Each was researched properly, one after another, and each got a clear answer.
It took until the seventh to notice that six of them had died of exactly the same thing. Every conversation had been sound. The pattern only existed across them, and there was nowhere it could be seen.
That is the part no amount of thinking gets you to, because it is not visible from inside any single idea. It needs something that remembers.
What it does differently
It searches before it answers. Not from memory — a company you half remember may have been acquired, repriced or closed, and a competitor named from recollection is worse than none at all.
Then it separates what it found from what it assumed, and shows you which is which. Market sizes are almost always assumptions, however careful the arithmetic, and Prior says so rather than dressing them up.
There is no score out of a hundred. Every other tool in this space gives you one, and a score is exactly the kind of confident number nobody can check — which is the thing this was built to avoid.
What it is honest about
It will often tell you to stop. That is not pessimism, it is arithmetic: most ideas have already occurred to somebody with more money and a head start.
But it will also tell you when there is a way past them, and it is specific about what that way is. A market with five competitors and one unserved buyer is a better place to be than an empty one, and knowing which you are looking at is the whole job.
And it improves as you use it. After three checks it starts telling you what your ideas have in common — which is the finding that took an evening and seven conversations to arrive at by hand.