A local SIM bought in-country is often cheaper per gigabyte. A travel eSIM is cheaper in total cost for most trips, once you count what the local SIM actually requires.
Buying locally usually means: finding an official store rather than an airport kiosk with tourist pricing, showing your passport for registration (mandatory in many countries), losing your own number while the SIM is in the phone, and spending an hour of a short trip doing it.
A local SIM makes clear sense for stays of a month or more, or if you need a local phone number for deliveries and bookings. For a trip of one to three weeks, the eSIM usually wins on total cost including your time — and you keep your own number active for banking codes.