Yes, as @billinghamj said, this are two different problems.
We have a bug that makes us show wrong icons here and there. We’ll fix that
The process of sourcing icons is currently manual. We may at some point build some kind of crowdsourcing for everybody to help us fixing the info. You’ll see the first baby-step on that direction really soon.
Regarding the inconsistency of vendors with logo and vendors without it… that’s something we need to live with and that’s why we use the category logos.
Logos (usually from Twitter) only work for big chains and places where the mark is recognisable. Think about it like a classic 20-80 Pareto, we want to show icons for the 20% of merchants that represent 80% of your activity, the remaining 20% are usually corner shops, kiosks and small places without any recognisable mark (they don’t have Twitter or Facebook either, or if they have it the icon is an ugly picture that becomes useless once we scale it down).