Figure a "mental health crisis" human conversation takes 30 minutes. Three million incidents per week would require 37,500 qualified mental health counselors on the phones working a 40 hour shift that week. Figure they make $75k/year each. You're now spending $3 billion per year on crisis response, and you're employing like 10% of all of the health counselors in the US. And all you're providing is 30 minute chats.
Mark Zuckerberg can spend $80B on the failed metaverse experiment, but can't spare some relative pocket change on solving the psychosis issue his products caused.
$3bn/yr is a lot of people money, but it is nothing for government money.
Edit: Last round of OpenAI funding was $122bn[2] and in the same article they are saying that they are generating $2bn in revenue per month. While that's not profit, it is worth mentioning that what you are saying "doesn't scale" is about 12% of the revenue of something that does scale. A single company. And mind you if we implemented what you're proposing it would be available to all the AI companies and more. Making it only a smaller drop in the bucket, not larger.
[0] Not to mention that better mental health care services will result in savings elsewhere. It's always way more expensive to fix a broken pipe that's flooding your house than it is to fix a pipe with a small crack. "Don't fix what ain't broken" is used too broadly. Maintenance is always cheaper than repair, but people just can't seem to understand this.
[1] https://www.usaspending.gov/federal_account/012-3510
[2] https://openai.com/index/accelerating-the-next-phase-ai/