My bet is they knew and did not care.
"Never attribute to malice that which is adequately explained by stupidity."
As usual a computation was made as to how much a "problem" would cost versus the extra cash we collect. And to that point, at least one of those kids was on a paid plan.
This is sensible argument which fits into my "you cannot always know the pitfalls before you start seeing people fall into them" concept. The idea being that they discovered the issue at some point, at which people people were already falling in the pitfall. I am 100% on board with this hypothesis.
The part you are unhappy about is that the publicly traded companies acted exactly like publicly traded companies do: profit is the priority. As a result, their response to the discovery was to calculate the loses from simply discontinuing service entirely until they fixed it, versus amount they would likely need to pay from the statistical number of resulting deaths. Publicly traded companies put money before everything. GM did this exact thing with car ignition switches.
I understand this anger and frustration which I share but if you do not know this already then I hope you teaches you that publicly traded company will ALWAYS prioritize profits. Private companies are hit or miss depending on who is in charge but a few years after becoming a publicly traded company they do anything and everything to prioritize profit. This is the unfortunate result of an unintentional but algorithmic refinement of leadership behavior. The mandate to promote the stock price is the result of several regulatory and legal obligations for leadership withing publicly traded corporations. Invariably, decency, ethics, and morality play second fiddle (at best) to profits. It's common for original leadership to grow tired of what they see happening to the company and thus are replaced by individuals without ethical qualms.
If you desire any real change to this approach then you will need to A) realize it won't be immediate or even soon and B) vote for more liberal-minded leadership everywhere. The more people you can get to vote, the better. An alternative is that you could get involved in politics and try to change things yourself. I know these are not the answers you want but I fear this is the reality of the situation.