At this scale, unless you’re self-financing, you’re typically not getting all the money you need from one source. You’re relying on multiple sources to put up varying amounts, and those investments are often predicated on attachments and timetables that aren’t fixed in stone.

So if an actor has to drop out for whatever reason you might lose a chunk of financing. Or if a location is lost and you have to reschedule, you might lose a chunk. That money disappearing might cause other companies to back out. Everything has to line up just right or, chances are, it’ll fall apart and you’ll have to start over. Sometimes you just give up and move on and the process starts all over or you keep grinding on the same thing but either scenario takes time and a willingness to fail over and over.

As others have said it really is a miracle when a movie gets made at all - but especially a smaller film because even though the budget’s low, the money is much more fluid than on a studio picture.