Why is the fine for downloading music so high?

To my best understanding, artists who make the music are robbed of royalties by illegal downloading. I can't say that I understand it perfectly but generally it has to do with matters of copy-wright infringement and/or use of artistic material without permission, etc. You may think that one person who downloads a song is not affecting music sales much, but if you consider that thousands of people are downloading songs without some permission from the artist and/or the music company then it amounts to lots of lost revenue for the artist and/or music company. Also, I am mostly sure that some kind of "tax-evasion" is involved by downloading music rather than buying from a music store.