Yeah, it is probably only a SEO issue. Study why other apps are showing first. Adding shopping list in the end of the name and in the description of the app will probably fix it.
google has access to more valuable data here than they do with web searches. if the majority of users search for "shopping list" and end up installing 5 different apps, which do they usually keep installed? rank that one higher for future searches. you can't fake the number of app installs like spammers can gain junk inbound links for pagerank.
the algorithm was totally broken. luckily for most of us they started fixing it yesterday and today.