Self-built cars are usually a completely different process, and also don't involve import.

But, the author of the article also massively overstates the requirements for a legal vehicle under the Low Speed Vehicle rules. The full FMVSS rules are gargantuan, complex, and hard to meet, but the LSV rules really aren't.

They basically need to not go 25mph, meet dimension and weight requirements, and have lights, reflectors, seat belts, and an approved windshield. https://www.law.cornell.edu/cfr/text/49/571.500

The manufacturer then self-attests that the vehicle meets FMVSS, and submits paperwork documenting their VIN format. Unless there are complaints or an investigation, that's pretty much it.

If you build it yourself then some /many of the regulations don’t apply. For example you don’t need airbags (in Massachusetts). It varies by state:

https://www.semasan.com/resources/everything-you-need-regist...

Roughly the same thing is true for airplanes - experimental (“home built”) have to be airworthy but not certificated.

They say it’s due to long tradition of DIY vehicles in America.

Generally they aren't. Here's an example:

> Factory Five products are expressly sold for custom car-building, racing and off-road use and are not intended to be used in conventional passenger or other legal highway applications.

https://www.factoryfive.com/terms-conditions

Varies by state. Some states allow you to have a kit car inspected and certified to drive on the street. Others require that the car be built from the frame of an already street legal vehicle. Some places put strict limits on the amount of miles it can be driven a year, and you'll likely need to shop around for specialty insurance to cover driving it.

In addition to what other commenters mentioned, in some states there is a legal gray area for registering a vehicle as just modifications on top of a donor vehicle that's already street legal. Commonly you start with a donor as a base anyway and no one is going to independently verify that your mods align with DOT standards.

You are paying for a 1 off inspection. If you go buy a Honda Civic you can skip the inspection, because it follows the street legal requirements.