If you don't agree to, refuse to follow, or ignore McDonald's terms, they will refuse to allow you to operate using their brand (ie. franchise).
There is no law that forces McDonald's to extend you a franchise license. It's their right to run their brand how they want.
Part of the franchise contract would be an agreement to use their approved vendor/parts list.
> or to harm others
Their policy exists for exactly this reason - prevent food borne illness from difficult to clean and maintain machines, ie. soft serve machines.
Anyone who has worked in a restaurant with a soft serve machine knows how much of a PITA they are to maintain and clean. Which means they don't get properly maintained or cleaned on average. McDonald's policies force franchises to maintain the machines. It's really simple, and it's really good.
I agree with you that this idea makes no sense. But I think your argument doesn't make sense. McDonalds can't deny someone a franchise license on the basis of them being black. They are compelled to not consider race when offering franchise licenses regardless of whether or not they'd like to. (I say that because, as far as I know, having non-race-blind preferences on who to do business with is not a crime, only acting on it is.) I see no reason a similar law couldn't theoretically also force them to not consider whether owners modify their ice cream machines.
If some law passed and McDondald's was going to lose control of franchises, consistency and their brand, they'd probably pivot to a mostly or entirely corporate-owned/operated model.
However, it's unreasonable to assert a franchise should be able to use whatever devices, machines, standards and consistency they want... which is what is being advocated here it seems.
You can go anywhere in the world and get a Big Mac or McFlury and expect it to be the same consistency as anywhere else. That's what McDonald's sells - consistency. If they lose that control, then they are not a brand anymore, just a loosely connected chain of independent restaurants doing whatever they want. That's not in anyone's best interest.
McDonald's can deny a license for pretty much any reason, or no reason, and nobody would be able to compel them otherwise. It is their brand, and nobody has a right to operate using that brand unless McDonald's allows it. That's the entire point of a franchise - use someone else's brand.
Ever go to a fast food restaurant and get watered down soda? That's what happens when the franchise owner has autonomy over those types of decisions. Save a few cents and piss off customers. Who do you get mad at - the franchise owner or the brand?
While gross, nobody gets sick from watered down soda - people can get sick from improperly cleaned soft serve machines. McDonald's avoids that by exerting this level of control.
There is no law that forces McDonald's to extend you a franchise license. It's their right to run their brand how they want.
Part of the franchise contract would be an agreement to use their approved vendor/parts list.
> or to harm others
Their policy exists for exactly this reason - prevent food borne illness from difficult to clean and maintain machines, ie. soft serve machines.
Anyone who has worked in a restaurant with a soft serve machine knows how much of a PITA they are to maintain and clean. Which means they don't get properly maintained or cleaned on average. McDonald's policies force franchises to maintain the machines. It's really simple, and it's really good.