Not clear if you mean a smartphone or any mobile phone.
They are just an expensive solution to a problem
That?s wrong on both counts. Smartphones aren't more expensive than other computers and simple mobile phones can be free, a gift from someone who has upgraded. Same with smartphones.
And its silly to claim that they are a solution to a problem that never existed, smartphones do covid checkins much better than anything else and simple mobile phones do calls when you aren't home much better than anything else.
Smartphones do navigation much better than map books too.