If Elon Musk can taunt the Securities and Exchange Commission via tweet even after it fined him $20 million and accused him of fraud, then Amazon.com (NASDAQ:AMZN) can certainly tell the regulatory agency to go pound salt when it demands disclosure on how much its Prime membership program contributes to net sales.

After Amazon touted in a press release last April that it had over 100 million Prime members worldwide and that over 5 billion items were shipped via the service in 2017, the SEC told Amazon that it had, in future, to disclose what percentage of net sales could be attributed to Prime members compared to that from non-Prime members. Amazon wrote back saying thanks, but no thanks, that data isn't "meaningful or useful information," so it was going to respectfully decline to comply.

While the SEC let the matter go for the time being, Amazon may not be able to avoid providing investors with useful information much longer.

Transparency is coming, like it or not

Amazon.com has long refused to share with the public anything other than broad generalizations about its operations. While it provides revenue and profit details as required, and breaks out how much Amazon Web Services and third-party sellers contribute to the total, it typically falls back on airy, undefined numbers when it achieves a milestone.

For example, the day after Christmas it released its list of accomplishments this year, touting that customers bought "millions of Amazon Devices" and it shipped "millions of unique items" through Prime to give it a "record-breaking holiday season." Beyond the puffery, though, we really don't know what Amazon achieved. How many people actually joined Prime at $119 per year? How many Echo smart speakers were sold? We're given nothing and it's left to market analysts and researchers to make a guess.

But the SEC put into effect last year new standards on revenue recognition that aim for greater simplicity and more transparency. Accounting Standards Codification Topic 606, or ASC 606, had arguably its biggest impact when Oracle (NYSE:ORCL) reported full-year earnings last summer, and then restated them the next day with $500 million eliminated from its top line because of the new rule. The abrupt change caused some analysts to rethink their entire outlook on the company.

Oracle also changed the way it reported its "X-as-a-Service" revenue, combining into one figure -- revenues realized from software, platform, and infrastructure -- where previously it had reported them separately. In relation to that, an analyst with Synergy Research told TechCrunch, "Generally speaking, when a company chooses to reduce the amount of financial detail it shares on its key strategic initiatives, that is not a good sign."

amazon prime A general view of atmosphere during the Amazon Prime Summer Soiree hosted by Erin and Sara Foster held at Sunset Towers on July 16, 2015 in West Hollywood, California. Photo: Tommaso Boddi/Getty Images for Amazon

Prime is not of primary importance

In Amazon's response to the SEC, it said that "management does not track the percentage of net sales that are attributable to Prime members and, therefore, Prime membership status is not tied into our financial reporting systems."

It goes on to say the Prime program, like its Alexa-enabled devices, Kindle e-readers, and other services, is just one cog in a much larger machine that's focused on selling goods and services, so if a sale comes from a Prime member it doesn't tell you much about the business.

But a strong argument can be made that the Prime loyalty program is a "key strategic initiative," as the Synergy analyst referenced when talking about Oracle, one essential to the e-tailer's long-term success. Prime members, after all, are estimated to far outspend their non-member counterparts, forking over some $1,300 a year, compared to $700 for those who aren't Prime members. Obfuscating Prime'simportance to its sales and growth is disingenuous of Amazon, though it isn't alone in pushing back on the SEC wanting to see more information. Alphabet (NASDAQ: GOOG) (NASDAQ: GOOGL) rebuffed a request to learn how much money it got from YouTube.

Key takeaway

Although the regulatory agency has not forced the issue yet, that could change, and investors would be better served by having greater insight into just how Amazon.com is earning its money. If CEO Jeff Bezos doesn't like it, he can always just tweet out what he thinks of the SEC's efforts.

This article originally appeared in the Motley Fool.

John Mackey, CEO of Whole Foods Market, an Amazon subsidiary, is a member of The Motley Fool's board of directors. Suzanne Frey, an executive at Alphabet, is a member of The Motley Fool's board of directors. Rich Duprey has no position in any of the stocks mentioned. The Motley Fool owns shares of and recommends Alphabet (A shares), Alphabet (C shares), and Amazon. The Motley Fool owns shares of Oracle and has the following options: long January 2020 $30 calls on Oracle. The Motley Fool has a disclosure policy.