The answer is that once you move past a modest shipping op the people with actual visibility on that would be the warehouse that's fulfilling, also typically people who don't have the power to cancel orders themselves.

Ecomm orders want to drop to the distribution center as soon as possible, which means you can't wait until you have a whole bunch of them just so you can analyze which addresses are on multiple orders. You would either need to 1) detect this in the warehouse systems (I spent my career working on these, so I can say with high certainty that is almost definitely Not going to happen, especially if they go through a 3PL) OR 2) you have to cancel orders after they have already dropped to the warehouse (which means wasted labor in the best-case scenario).

None of that is worth the effort to a company who is fundamentally still getting paid the same for the product regardless of if the purchaser is a scalper or not.

Why would any people need to see the addresses at all? The solution being proposed is something that you'd automate with a series of heuristics. And your point about the company making the same money for shipping to scalpers vs non scalpers seems like it would only apply to the shipping company, but if you view from the perspective of the product company, obviously they have an incentive to avoid scalpers because it negatively impacts the brand and the price spikes are money not captured by the product company and may even reduce further spending (eg if a buyer spaffed half their budget on an overpriced console, that's less for buying games which benefit the product company, eg Steam in this case)