Do I trust this computer?, my iPhone asks me for what has to be the thousandth time using the same computer logged into the same Apple ID. Enter your passcode, it demands once again, reflecting the hardware, software, and services working together in a way only Apple can deliver.
The sadder part is that it used to work sensibly ages ago. You only got asked once and it stuck more or less forever. But then someone at Apple decided that that's clearly not enough security, because you absolutely can never have enough according to some people, and in the typical Apple fashion implemented the current behavior without giving the users an opportunity to evaluate their own risks.