This is an hilariously anti-Mustachian service.
For starters, according to their website, their "savings account" pays no interest at all. But not to worry, they "plan to offer ways to get a return on your savings in the future". In other words, there's actually no reason to use this service at all versus keeping money in your checking account.
Secondly, who actually engages in transactions in their checking account on a regular basis? Mustachians would be paying for things by credit card, and only paying the bill in full once per month. So an algorithm transferring money based on daily checking account activity doesn't make any sense.
Third, according to the "How it Works" page, they transfer $5 to $50 per day, but only if you can afford it! Fifty dollars per day is only $18,250 per year, a pretty meagre amount of savings.
What a scam of a product.
Can you share the high interest checking account you use with me? I'd love to get in on that. Especially if it has 5-10 hoops to jump through each month to get that additional 1% or so.
I keep my money in actual investments, not in bank accounts. Bank accounts are for current transactions like paying credit card bills or utilities or transferring money around. They are not instruments for building wealth, at least not in 2015. Most (though not all) of my money is in equities.
The tool is clearly a scam.
Thank you for proving my point. So to answer your initial question of "who actually engages in transactions in their checking account on a regular basis?" You do. And most everyone else.
Also, when I refer to 'savings' I don't literally mean whatever extra money it comes up with should go directly into a traditional savings account. It can go towards debts, stocks, equites, retirement, etc.
And yes, you could use YNAB and I whole heartedly believe everyone should (I almost worked for them, as an aside). BUT, not everyone wants to or even knows how to take the time, energy or effort involved to track all their spending and work out their budget manually from month to month.
It helps show people who might not want to or even know where to begin how much they could saving with almost no effort on the part of the user. For doing so, they take the interest earned on the money they transfer for you. For me, it's worth losing the 5 cents I might have earned in interest on that money to show me I could be saving and extra $20, $30 or $400 a month.
It's not likely it will offer much benefit to mustachians who have their spending and savings tightly managed. But for those who have no plan or put no thought into what they could be saving instead of sitting in their checking account, it could make a big difference.
Believe it or not, not everyones situation and spending habits are the same as Cathy and zdrave.