Companies can get away with price differences for physical goods, for a bunch of obvious reasons which don't apply to digital goods.

Charge different prices for a downloadable digital good and allow customers to shop around, and you have a de-facto one price for everyone scheme: the lowest price of all the regions.

If someone voluntarily pays a "France" price rather than an "Estonia" price, you could achieve the same thing by setting up a pay-what-you-want cart with the Estonia price as the minimum. There are many sales tricks that can be used to persuade people to pay more (up to their willingness to pay), that would cost you nothing or next-to-nothing, to get more money out of customers even if they are only required to pay the Estonia price.

Imagine that based on local income a digital product that has virtually no marginal cost is $25 in one market and $50 in another for whatever currency you please.

If someone in market B can by clicking over to a different storefront for market A then logically the vendor will no longer offer the good at the lessor rate in market A.

They will have to figure out what price maximizes revenue in both and it will surely disadvantage buyers in market A because the vendor gains as much for one market B buyer as two market A buyers.

If 40% of your buyers are from poor land then losing every one of them is as costly as dropping richland users prices by 1/3.

What if the vendor offered coupons available only locally to make it more feasible to differentiate prices while keeping stuff portable?

Because this isn't what happens. Price discrimination, if done perfectly, minimises the value the consumer can get and maximises the value the seller can extract from them. Overall it is a negative for consumers.

Vendors of digital goods could use other ways to price it. For example, the product costs $50, but show us your tax returns and we'll discount to $25.

'Student discount' is the same sort of thing, and common across Europe.

The reason why people in Iowa don't pay the same price than in Cali is because it is impractical, and possibly even prevented by some regulations, to buy the car in Iowa and drive it to California.

With digital downloads, and even physical games, that's not the case: I can buy my game in Czech Republic and have it mailed to Denmark (to stick with the example someone else posted) with minimal friction.

> possibly even prevented by some regulations, to buy the car in Iowa and drive it to California.

I have no idea what's you're talking about. Interstate travel is legal, and interstate purchases or transfers for cars is very common.

I have very limited knowledge of how car registration in the US works, but AFAIK some states, particularly California, have stricter emission limits. Does every car sold anywhere in the US meet them, or do manufacturers make cheaper "non-Cali" models that lack some emission controls but can't be registered in California?

Even if there is no regulatory hurdle, there's a significant practical one, which is getting the car over.

Even with the different emission standards, you're allowed to own the vehicle. However, if it does not pass inspection (if the state has inspections) then it won't be legal to drive as it didn't pass inspection. However, you're still allowed to own the car.

(Also, I wish I hadn't been down voted without a response. If I'm wrong, correct me.)

The digital goods sellers are going to have a field day if these laws end up allowing "Sure you can 'own' the game, but you can't 'play' it".

Regardless of what the MPAA would have you believe, digital products and cars are a bit different.