Different solutions for different problems. You have a different design requirement when you are designing something for use by the most vulnerable and those without access to reasonable technology. This absolutely needs to be factored in when choosing how to build something, however, this is a tiny subset of users, and this is for essential life-is-in-the-balance types of service. The vast majority of users will hav…
In both scenarios, I'm trying to complete my task as quickly as possible while I still have a good connection. A simple HTML page (with JS layered on top for fancier stuff) would be plenty to get the job done. Instead you get hindered by sites that aren't optimised in any way for slow devices or slow internet.
Heard that Facebook before had "2G Tuesdays" where the product teams throttled their internal net speeds to 2G while browsing the site to see what it was like — that should be the standard for dev teams. The trouble is so many things are designed and tested by people on T1 broadband in a downtown office, but that's not the set-up of a majority of their users.