Untrue - there isn't a personal finance solution that doesn't have mistakes. Not one. I've literally tried them all. Its mostly because the syncing with accounts is very very brittle and a lot of things like stock plans etc aren't supported well so your daily view will always be somewhat off.
There are insights to derive from the data - like how much do you really spend. But again its really hard to get there because the numbers are always off and most people don't actually want to know.
You are severely underestimating the average person's agency with their money.
I use an app but I also have an excel sheet where I track everything very carefully every week or so.
Trust my excel sheet much much more.
Honestly for everyone I know this is how they do it. There is one guy who built his own app and his is perfect because he has solved for his specific bank accounts.
He knows every $ coming in and going out - its pretty impressive.
There are insights to derive from the data - like how much do you really spend. But again its really hard to get there because the numbers are always off and most people don't actually want to know.
You are severely underestimating the average person's agency with their money.