The problem with regards to Class III is deeper than the fact that they are prohibited from use on MUP's.
The federal Consumer Product Safety Act defines a "low speed electric bicycle" as a two or three wheeled vehicle with fully operable pedals, a top speed when powered solely by the motor under 20 mph (32 km/h) and an electric motor that produces less than 750 W (1.01 hp). The Act authorizes the Consumer Product Safety Commission to protect people who ride low-speed electric vehicles by issuing necessary safety regulations.
[57] The rules for e-bikes on public roads, sidewalks, and pathways are under state jurisdiction, and vary.
In conformance with legislation adopted by the U.S. Congress defining this category of electric-power bicycle (15 U.S.C. 2085(b)), CPSC rules stipulate that
low speed electric bicycles[58] (to include two- and three-wheel vehicles) are exempt from classification as
motor vehicles providing they have fully operable pedals, an electric motor of less than 750W (1 hp), and a top motor-powered speed of less than 20 miles per hour (32 km/h) when operated by a rider weighing 170 pounds.
[59] An electric bike remaining within these specifications is subject to the CPSC consumer product regulations for a
bicycle.
Commercially manufactured e-bikes exceeding these power and speed limits are regulated by the federal DOT and NHTSA as motor vehicles, and must meet additional safety requirements. The legislation enacting this amendment to the CPSC is also known as HR 727.[60] The text of HR 727 includes the statement: "This section shall supersede any State law or requirement with respect to low-speed electric bicycles to the extent that such State law or requirement is more stringent than the Federal law or requirements." (Note that this refers to
consumer product regulations enacted under the Consumer Product Safety Act. Preemption of more stringent state consumer product regulations does not limit State authority to regulate the
use of electric bicycles, or bicycles in general, under state vehicle codes.)
The above in
bold clearly designates the Federal regulations regarding eBike legality here and the Class I and II ones clearly meet that. The key factor here is the fact that bikes that meet these requirements are regulated by the CPSC, same as any bicycle motor or not. The problem as I see it with the new Class III laws is how it relates
bold to bold. The way I interpret this, and I am no lawyer, is that any state may have different regulations regarding eBikes but they cannot exceed the Federal Regs. As bold states eBikes that are able to exceed 20mph come under the jurisdiction of the DOT and in addition the NHTSA:
3. Requirements to lawfully import motorcycles or motor-driven cycles for on-road use.
If a motorcycle or motor driven cycle is capable of a top speed of 20 mph or greater and is equipped with components (such as lights, mirrors, and turn signals) that are needed for on-road use, NHTSA will regard it as having been primarily manufactured for such purposes. Motorcycles and motor-driven cycles with these capabilities and equipment cannot be lawfully imported into the U.S. unless they were originally manufactured to comply with all applicable FMVSS and bear a label certifying such compliance that is permanently affixed by the original manufacturer. The label must be affixed to a permanent member of the vehicle, as close as is practicable to the intersection of the steering post and the handle bars, so that its contents can be easily read without moving any part of the vehicle except for the steering mechanism. In addition, the vehicle’s manufacturer is required to submit to NHTSA identifying information on itself and the products it manufactures to the FMVSS (as required by 49 CFR Part 566), provide NHTSA with information the agency would need to decipher the VIN the manufacturer is required (under 49 CFR Part 565) to assign to each motor vehicle manufactured for sale in the U.S., and designate a U.S. resident as its agent for service of process (as required under 49 CFR 551.45).
DOT additional safety requirements are elements such as rims/tires that need DOT approval, full lighting package including brake and turn signal indicators, rearview mirror, horn and most specifically a VIN # that allows vehicles in general to be eligible for registration purposes. These requirements have generally been associated with MoPed class vehicles that are also excluded from MUP's and generally are used on public roads anyway.
The bike industry here via their BPSA mouthpiece no doubt has a better grip on the legalities involved here. In the EU the Speed Pedlec regulations https://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX:32013R0168&from=EN put them into the same sort of approval and are lumped in with ICE vehicles as well. That is why you see mirrors, lights and a license plate holder on them there but not generally seen on US spec bikes as they are skirting the DOT/NHTSA regs here.