It is absolutely insane that organizations are weaponizing this.
> Doesn't Google have any way to dispute the business ownership?
I can only speak for the US and it’s been a few years since I’ve done it, but yes Google does have a way. You can report an issue, and “claim” a business. Google will literally send a postcard with a unique ID to the registered physical address, and whoever gets that postcard can take ownership.
> Can I take over any business on the maps by just registering a domain that contains the business name?
Absolutely not (at least legally I assume). It’s probably trademark infringement and potentially fraud to misrepresent that business, and also Google has other methods to verify ownership (see above).