1) The ones that collect the data automatically require me to violate my bank's online TOS to gather the data (e.g. Mint), which potentially leaves me with no recourse should my bank account be compromised.
2) The ones that require me to input the data are just too much work.
I've been using YNAB (You Need A Budget) for a few months, and it makes you input everything. I initially resisted and thought the same thing as you. However I forced myself to try it because so many people recommended it so highly.
It is at it's core a glorified spreadsheet, but it's a very well designed spreadsheet with great support and a solid budgeting methodology behind it. Entering transactions manually has not been that painful, and the big benefit of doing this is that you are actively participating with your budget. WIth mint you spend money and then see how it fits into your budget. With YNAB you give that dollar a job as soon as you get it, and you manually input it when you spend it. It really keeps you aware of your budget and where you are in it and in my experience makes it much easier to stick to it.
I found every time I tried to use Mint to budget (privacy issues aside) it never worked out because it was a very passive thing. Set up some categories. Spend money. Wait for email to tell me I'm over budget, oops.
YNAB is very active so it keeps you honest. And unlike mint, YNAB is designed to be a fluid budget. You can and are encouraged to adjust budget amounts and categories on the fly as life happens, which is something painful to do in mint or other apps.
It is a bit of a pain to have to manually handle transactions (though you can import CSV) but I find the benefits of doing that outweighs the hassle.
The pain of budgeting is in tracking outflows, at least for me. I make a combination of debit, credit, and cash purchases, and even just through those three channels it's easy to lose track of what went where.
As you note in your app description, people typically give up "tracking expenses... because it was too much effort." So how does your app solve this pain? Would be nice if it were explained.