The nvidia-smi utility normally gets installed in the driver install step. It cannot/does not get installed in any other installation step.
nvidia-smi is not mandatory for basic driver operation (obviously - it is an informational utility).
If you install a NVIDIA GPU driver using a repository that is maintained by NVIDIA, you will always get the nvidia-smi utility with any recent driver install.
Unfortunately, the ppa repository is not maintained by NVIDIA. The maintainers of that repository may have deleted that executable from their install package. (and there may be other differences as well)
For CUDA usage, I recommend that people not install their drivers from ppa.
Instead, follow published instructions by NVIDIA.
Get your installers from [url]Official Drivers | NVIDIA (only drivers) or [url]http://www.nvidia.com/getcuda[/url] (full CUDA toolkit installers, including drivers)
For CUDA, follow published install instructions:
[url]CUDA Toolkit Documentation
You won’t find any NVIDIA references suggesting install from ppa, AFAIK.