Trump is interviewing for President of a large swathe of America's cranky inner toddler.
These are largely people who know there's somehing wrong with America, with politics, with the world. They can't articulate really what, and they don't or won't grasp the nuance and complexity that is life these days. Things "used to be simpler" and they don't want hundreds of pages of policy documenting fixes, they don't want to hear about the complexities of budgets and taxes and international policies. These are all overly complicated, nerdy concepts, and none of their previous votes have succeeded in making the world the simpler place they want.
Trump constantly feeds them reassurances that they're right, the world is wrong, and he'll fix it. No details is a positive, because they're messy and frustrating and people just want somebody to fix it.
Trump isn't going the normal presidential route--he's not trying to win with emotion-tinged policies, he's just trying to ride raw emotion in without policy. He'll Make It Better; any more details than that is scary and shouldn't be mentioned because it requires acknowledging possible obstacles to Making It Better.
Most jobs, the person doing the hiring has either a grasp of what the job does, or is evaluating against a set of metrics created by somebody who does that determine minimum qualification. The average American doesn't really understand how Presidenting works, and the actually job requirements set forth in our laws are pretty low.
