People already trust companies with their money. If banks supported crypto natively the no-install/web app model works great. The last three points are rendered irrelevant here if banks are able to make the experience easy and guarantee some value.
Those who don't want the protection of a bank are trading off points 1/2/4 for point 3.
Users don't have a problem installing apps on their phone.
The rest are valid problems, with #2 and #4 being directly linked to low adoption.
Web pages and browser extensions are pretty low barrier to entry.
Exchanging cost is not too bad, but probably the biggest hurdle still.
Privacy I don't think is a problem here. One random address to another is good enough for these type of transactions.
Pegging to another currency means centralization, though that is acceptable to plenty of people.
You said you wished there was a solution, all I'm saying is there is a clear path to how it could be done.
1: You need to download and install software to use current cryptocurrencies. And users hate that.
2: Turning Fiat into Bitcoin and vica versa is not easy.
3: It is less private then cash.
4: Volatility of the value. Users would want something pegged to their currency of choice.