Why should consumers pay a tax to keep SMBs alive? If Amazon can offer the same product for cheaper than anyone else, what right does a SMB have to charge consumers more for it?

hmmm, talking about "rights" might not be the way to look at this. talking about systemic effects might be a better way. consumers aren't just consumers after all, they're also usually employees. What are the effects, both positive and negative of having such a large company be able to dominate supply chains so much that they can often bring equivalent quality products to market for cheaper. It's a complicated question, not as easy as the moralizing on either side. Amazon and WalMart bad! Amazon and WalMart good!

Then remove all workforce and automate everything..

No seriously, read this: http://www.theguardian.com/sustainable-business/sustainable-... ,It's why second hand clothing is sold in africa and not given away.

A robust market is in everyone's interest. See: railroads 100 years ago.

SMBs need to add value on either location and convenience, or service. It's something that has been long studied by management experts (see Porter's Competitive Advantage):

https://en.wikipedia.org/wiki/Competitive_advantage

If you want them to compete on Amazon's ground, they will lose.