Those graphs are scaled so the largest result is always at 100 - so you can't really tell how many people are doing this sort of thing from this graph. It could be dozens or millions. Having your search country set to only South Africa also seems pretty non-representative.

Could also be due to the fact that the search bar and the address bar is the same, if you forget, or don’t know to put.com at the end, it will take you straight to the search page.

In college late 90s I knew one person who would navigate to Yahoo and search for Google.

Blame chrome. Autofill doesn't include .com? Welp, guess I'll just hit the top search link instead then.

I do this when I don't remember if it's .com .net or whatever

Considering how many web addresses with similar spellings lead to malware sites, it's usually safer to do a search rather than typing a long address from memory.

Android keyboards are still so terrible that I often type "site com" because I hit the space instead of period

Though as a site analyst for many years, this is accurate. Our domain was the top incoming search phrase for a long time. Varied by browser, like IE since it had a separate search bar. Chrome just took them right to our site