Well, don't be so sure! ....
For last several years Amazon grocery purchases at my small town is being exclusively sourced from a local 'More' supermarket (Amazon-owned). As a result choices became extremely limited, store-brand products are often poor quality, and prices are typically high (sometimes absurdly so). So I rarely place a grocery order with them these days.
Be that as it may, one evening a few months back I stopped short of placing a grocery order on my cart because the prices seemed too high in comparison with local offline stores. --- My Prime membership happened to expire that day, and I chose not to renew it due to my overall level of satisfaction with Amazon.
Next morning I was not a Prime member anymore, and I was amazed to find that my grocery cart prices came down drastically overnight to be in sync with the local market conditions! ... I started wondering whether Amazon actually (at least partially) finance their Prime service costs this way! Needless to say I never went back to the Prime membership again.
Of course, this was an one-off experience and there is no easy way for me to repeat the experiment to be absolutely sure. But Amazon have lost my trust and respect bigtime that day, and I don't place them on a higher pedestal compared to anybody else anymore.
... My overall Amazon orders have drastically decreased ever since.
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