[1]http://www.statista.com/statistics/269405/number-of-stores-o...
This isn't true by a longshot. The 300m figure is every man, woman, teenager, child, and infant in America, and you only need one person per family going for a weekly grocery trip. And that's of course ignoring the people who don't do weekly groceries. On top of THAT, the 30% number doesn't seem particularly reasonable either (though that one is at least the only remotely plausible thing you've said).
If all you can contribute to the conversation is pretending that stylistic choices are errors, it's probably better to contribute nothing at all.
According to statista[1], walmart.com does 91.6 million unique visitors per month.
According to statisticbrain[2], Wal-Mart stores (location not specified) have 100 million customers (not visits) per week.
[1] - http://www.statista.com/statistics/271450/monthly-unique-vis...
[2] - http://www.statisticbrain.com/wal-mart-company-statistics/
> Today, nearly 260 million customers visit our more than 11,500 stores under 63 banners in 28 countries and e-commerce sites in 11 countries each week.
> According to statisticbrain[2], Wal-Mart stores (location not specified) have 100 million customers (not visits) per week.
The source you cited looks like the location they're referring to is worldwide. They cite "Total Wal-mart sales annually" and that lines up with their total global revenue, so I think it's a fair assumption that their "Total numbers of customer per week" would likewise be globally.