As long as you use our service, you have access to that dispute system. Also we aren't just for cleaning or repeat services like homejoy. People will still use the app when they're in a quick need of something, as this is the niche its meant to fill.
I'm currently working on adding in a rating system. The back-end is set up in such a way that your credit card is authorized when you make a task, and charged when you hit "Confirm Task". If your task is accepted and its been 5 days and you haven't hit confirm or dispute, it automatically charges the card.