It's different because of the source. People trust the bank's website because they see the URL and know that it's genuine. People trust brick and mortar stores

It's different because of the source. People trust the bank's website because they see the URL and know that it's genuine. People trust brick and mortar stores because they trust Best Buy to deliver products from the people they say they're from. People trust the app store on their phone just like a brick and mortar store... that is, they expect that somebody is ensuring the validity of the products that are being shown to them. There is no other way for the consumer to validate this information, so the store provider must.