That's comparing - pardon the pun - Apples to Apples.
There's choice and variety. I can get a Mac Mini for the same cost as a mid-range iPad. I can get a desktop PC for less than most iPads, even the entry-level one.
Despite all the extra features they offer, a smartphone's primary function is still as a phone.
There are many choices out there. There's also nothing stopping a phone manufacturer from making their own software that allows all the sideloading and hacking you can handle.
This seems like punishing Apple for their innovation. While I would like Apple and other companies to implement many of the things this suggested law outlines, I would rather them do it from public pressure than having their hand forced. I used this example in another thread, but its like watching a restaurant grow successful over time by having the best service, food and atmosphere, and then being forced to allow others to sell their food items in your restaurant.