[Nextgrid]

In practice, there is little difference between "junk email" which I assume you mean scams/phishing/pills/viagra/etc adverts and that Amazon email. Both take space in your inbox, may send you a notification and require time and brain power to deal with. Whether the latter example may comply with some jurisdiction's definition of "spam" is irrelevant.

The "mark as spam" button gives users the ability to keep their inbox clean and you shouldn't be faulting them for using it.

Not to mention, even if we agree for a minute that the report spam button should only be used for emails that conform to the legal definition of spam, which law should we be following? The US' definition of spam is much more liberal than the EU GDPR's one for example.