Many countries have functioning giro systems. The U.S. is just an outlier.
What about manufacturer rebates?
The only time I really saw checks used was when I was a child ~30-35 years ago and my parents used them. I did once cash a check from an elderly relative, but that was very unusual and only happened once. I didn't even know it was still possible to do that, my reaction was more like if someone had handed me a stack of punch cards to run on my computer.
There hasn't been anything an average person used checks for in the last decades in Germany. Except a few elderly people, nobody uses checks and there are no rebates via checks at all.
Receiving a check however is even rarer.
Granny can always give you cash or just send it directly to you account in the same way.
As it turned out, my bank rejected both because they were made out to [middle name] [surname] rather than [firstname] [surname]. Ironically the former is unique (probably) whereas they had another customer with the latter.
On a more serious note, the last time I saw a cheque in the UK was my grandfather balancing his cheque book in the mid 80s. It really has been that long since they were in general use in the UK, at least.
Just like with the prevalance of Apple/iPhones, the US banking system is global outlier.
Things you can't do with my banking app you can do with the web site:
- Extract your transactions to excel/csv
- Use OpenBanking
- See all my accounts on screen at once
- Sharedealing
- International transfers
But people are right, banks trust the mobile app more, and realy on it as an MFA device, so even if you use the website you still need the app.