Thanks @Marph .
Effilicious | Simplenote to Joplin import tutorial doesn't cover tags at all. However, Simple Note (JSON) to Joplin (ENEX) - python script has a workaround for tags. Basically...
- we have to export notes on simplenote to a json file (that is default).
- then use the aforementioned script to extract notes (from json file) that belong to a particular tag/s.
- repeat step 2, for all the tags.
- use the aforementioned script to extract notes that are untagged and the notes that are tagged but left out of the above steps.
- import the exported files to Joplin.