The regulatory overhead to grid-connect is a _significant_ portion of the price, both for the actual paperwork labor and because of the premium it imposes on the system components (you can't use inexpensive non-UL-listed panels)

Is this really a thing in the US? At least in Europe, rooftop solar like OP mentioned doesn't require grid-connection?

Only some states allow simple plug in roof top or balcony solar I believe. So depending on your area you might be required to do a grid hookup and lose access to it during outages.

Net metering hasn’t been allowed in my county in more than two years so that can’t be it.