I also think "we reserve the right to refuse service to anyone" applies no matter who you are. I don't support the idea of legislation that forces giving detailed policy responses, or any responses at all.
Google (and others) have formed a business around having policies so automated that half the people involved might not even know what the policy is, just "computer says no" or "computer flagged it and someone somewhere in the review process said no". I don't think that practice should be banned; on the contrary, it should be possible to try the approach of using automation to be able to scale.
And that's a potential opportunity for other competitors; one demonstrated path to success in competing with a company like Google is providing better support and real human interaction.
If it turns out that a company is succeeding in spite of awful service, it might be because their product is just that good to overcome that deficiency, or it might also be because their monopoly prevents people from competing with them even with a better product. That's worth examining. But I don't think that's an argument that people should be forced to explain why they don't want to do business with someone; I think that's an argument that we should make sure that it's possible to compete fairly and offer better service to people who want better service.
> On the other hand, this post talks about having a similar response from Microsoft, and those companies didn't collude
As I wrote, I got the ban from Microsoft minutes after Google even before I created an ad or told them what site I planned to advertise. So my guess is that they do exchange data about potential fraudsters.
> applies no matter who you are
In this case we're talking about a monopoly that is the internet's gatekeeper. If they decide they can refuse their service to us, we die, no guesses. Is that the right way?
It should never apply to monopolies. Governments should always go to all extent into making sure a market is competitive, or make sure things like that do not happen. The preference should obviously be the first one.
If you're abusing a monopoly in a way that prevents other people from coming in and doing better than you, that's the issue, not the specific manifestation of how you're abusing it.
This is the truth and it's very depressing. I would personally support either legislation forcing Google to be more transparent of these bans or legislation ripping the company apart so that they don't own the ad exchange, as well as sell ads themselves, as well as everything else they have integrated. One can only dream...