Because they don't know it's a deprecated language.
In fact they probably don't even know what "deprecated" means.
It wasn't that long ago that Python 2.7 was the default on the Raspberry Pi. (That may still be true - I haven't checked recently.)
There's a huge ecosystem of Python 2.7 tutorials, introductions, and sample code out there. Very little of it is prefaced with "Of course you should use Python 3 now."
I bet they know how versions work though, and that 3.7 is higher than 2.7. I just googled ‘Python tutorial’ and only one of the results on the first page was for python 2. The first result was ‘The Python Tutorial — Python 3.7.3 documentation’. If some non-programmer was going to start learning python, they’re most likely going to start with google. I can’t see them digging deeper into the results because they want to learn an older version of the language.
In fact they probably don't even know what "deprecated" means.
It wasn't that long ago that Python 2.7 was the default on the Raspberry Pi. (That may still be true - I haven't checked recently.)
There's a huge ecosystem of Python 2.7 tutorials, introductions, and sample code out there. Very little of it is prefaced with "Of course you should use Python 3 now."