The last time I installed bench, I did this out of confusion. Because I can’t do sudo bench setup production (err: ‘bench is not found’ when sudo).
So I did:
- pip3 install --user frappe-bench
- pip3 install frappe-bench
- sudo pip3 install --user frappe-bench
- sudo pip3 install frappe-bench
Hence maybe there were 4 install of bench 
It turned out that it is PATH as @vrms mentioned. I add the /usr/local/bin path into secure path in visudo and it works well.
This issue is mentioned by @fromthestone here (Installation on CentOS 8 from instruction not working - #5 by fromthestone)
Yesterday I installed a new bench with sudo pip3 install frappe-bench and add the path. The install went through well until production setup.