Except languages are ambiguous. When you say you want to undo a commit, do you mean undo like pretend nothing had happened or undo but please keep track of the change.
That's why the first thing I do when I'm learning something new is to read the documentation to find out what capabilities are available.
Just as a few others have mentioned, I too never have such problems using Taobao.
The way I use it is with the app, click to sort by number of sales, and usually buy from one of the top sellers. I don't usually talk to the sellers unless I have questions about the stuff I'm about to buy, and I turn off the notification for the app so 80% of the time I just never reply the seller. They might still send the message asking me to confirm the address, but they'll still send the package even if I don't reply.
As for the delivery time it depends on where you live and where the seller is in. When I lived in Shanghai most of the packages arrive in at most 2 days as I usually choose the sellers from Zhejiang, Jiangsu or Shanghai
The indicator indicates background activities. Eg. If you are using Google maps for navigation, the bar will show when you switch away from Google maps. But when you switch back, now it's happening in the foreground and the indicator disappears.
Camera can only be accessed by the foreground app.