You are surprised that cruise lines pay so little to their crew and force the public to essentially pay their salaries. A few others have been surprised as well. But you must realize that this practice has been commonplace on nearly every ship in the world for the past hundred years or so. This is not news.
It was popularized by the American multi-millionaire J.P. Morgan when he purchased the White Star Line in 1909 as they were building the Titanic.
25 years ago when I was a waiter at Royal Viking Line (the greatest and most elegant cruise company of that time), a standard 7-day cruise averaged about $6,000 per person and the average tip paid was nearly $20 per person per day.
I suspect that you are paying far less than $6,000 per person for your cruise - and probably getting as much or more than Royal Viking offered 25 years ago. You are also tipping far less than I received 25 years ago, but receiving reasonably good service from staff whose salaries have been cut by more than 50%.
Will this century-old tipping practice change appreciably over the next 50 years? No.
Will your protests or arguments make any difference? No.
Can a good Indonesian waiter earn more money at home than on a cruise ship? Yes.
Will the cruise lines continue to lose their best service staff because the passengers are too cheap to properly tip them? Yes.
Will service levels on cruise ships continue to deteriorate as the better service staff find better-paying jobs elsewhere? Yes.