Price discrimination at Dodger Stadium

The L.A. Times reports on price discrimination in baseball:

The Dodgers sell tickets in the field box section for $20, $30, $35, $37, $40 and $45, depending on whether you buy on game day, before game day or as part of a full-season, partial-season or group ticket package.

What's the ticket price? The Dodgers offer you 104 answers in all.

Inevitable as prices climb higher. To put those higher prices in perspective, with some numbers from when I was tiny and not yet aware of baseball,

In 1987, the Angels sold tickets for $8, $7, $5 and $3 and the Dodgers for $7, $6 and $4, with every seat on the same level at the same price.

Hmm. If I count the Dodger increase as 500 percent ($7 to $35, $6 to $30, $4 to $20), that's 8 percent every year for 20 years. And they wonder why you can't get kids interested in baseball anymore... maybe if they could go to more than one game a year there'd be a better chance.

Anyone know something about monetary policy?

Okay, so I'm a former econ major (albeit not a very attentive one), and I'm confused. The NYT has an article on the issuing of dollar coins, and the fact that they won't be successful until the dollar bill is withdrawn. The article includes this (to me) confusing note:

A banknote, since it is redeemable, counts as a government liability, and the Federal Reserve has to back it by buying securities, which earn interest. According to the Fed, there are now about eight billion dollar bills in circulation, so that interest income is considerable. Coins do not yield such income.

Huh? I always thought the purchase of securities (e.g. Treasury bonds) was just the Fed's vehicle to increase the quantity of money. From that perspective, whether you're issuing coins or bills is irrelevant. And what, exactly, is a banknote "redeemable" for? The USD is fiat money, i.e. "legal tender because we said so." Am I missing something here?