What they have is an immediate need for something, so it doesn't matter which stack is chosen.
In many cases they may say "can you fix this app the other contractor built", and then you will be using that stack only as far as that particular enhancement or fix.
They don't have git, or Jira, or ticketing systems, or code review or any of that.
All the work I am doing is for either people I've worked for before, or friends of those people.
I've looked at a few of the gig sites, but I am not prepared to take on tiny 1day work at $30/hour, and that is unfortunately the majority of the things I saw on those sites.
The best work to get is from non-tech companies; tech companies want lines of code delivered, non-tech companies want business value delivered. Guess which one is prepared to pay more for the same number of lines of code ...
I've had clients specifically ask for certain platforms (WordPress, Shopify, etc) but still assemble my own solutions regularly when it'll make me more productive up front.
The thing is, for many small to medium companies, they don't have a dev team in house. It doesn't make financial sense.
What sort of guidance do you expect the CTO to provide when his main technical capabilities is ensuring that procurement gets the correct spec laptops for employees, that the correct permissions are set for new employees on the microsoft accounts, that Teams works for everybody, that the support staff go on appropriate training for the software they use, that there is a migration strategy for the next version of Windows ...
That sort of person is not, and is not expected to be, qualified to code-review your PRs.
Even if they know how to use git, they won't have a git repo set up, and even if they somehow managed to do that, they won't have a clue how to use Jira or similar correctly, and even if they do know, they still won't be able to code-review properly.
This is why they'll pay more than what a tech company would - you'll be bringing more value to them, and they'll be trusting you much more than the average FAANG trusts their senior engineers.