I conclude therefore that a large proportion of Android users simply cannot purchase and download paid for apps to their phone

Not all countries have access to paid apps right now. Google has to speed up on making paid apps available to these countries, otherwise the ratio of apps purchased may just stay that way.

It doesn't seem to be consistent. Out of one search result I only have one modified link in the first page (searched "mac mini" ) on Firefox. The next search with the exact results returned the unmodified Wikipedia link. Could it be some caching mechanism?