I'd suggest the nature of free and paid services biases how many of each we think gets "shut down" post-acquisition. Free / freemium services will tend to have tens or hundreds of times as many "users" versus a paid service of the same value.
So when one gets shut down, we all notice because so many of us had an account (even if we weren't using it.) Whereas when a paid service closes, it impacts only a tiny fraction of us in comparison, so we don't hear the same hue and cry.
The fact is that for a large company like Google or Amazon, the $$$ income from most small startup acquisitions (ads or paid) isn't large enough to be a factor in the decision to continue running that product. Either they believe that it's going to turn into a business that does tens to hundreds of millions of dollars in sales a year, or they don't and it's better to move those developers and resources off to a project that might.
I've seen this firsthand - I've had to fight to maintain services that were making lots of money with a few staffers, because a large company just didn't think they were worth the hassle of supporting from a legal and administrative perspective. And I understood that point of view from a management perspective, in many cases.