That's because you don't understand what the spammers really do. They are thieves; responsible for over $10 billion annual costs to the Internet's infrastructure every year. Some estimate that over 80% of all email traffic, and the associated bandwidth consumption and server resources, is due to spam. And since that price isn't being paid by the spammer (nearly all get their connectivity through theft of services), it is being paid by the ISPs, and ultimately their customers.
as in junk regular mail I can look at it or delete/throw it away on my time line.
Junk mail doesn't come postage due; spam does (and worse, with no ability to refuse to accept it). By tolerating the spammers, you are tolerating criminal activity.