people expect the price to remain at 60 for most of the game's life, so they buy them at 60, and it sells a BUTTON whenever they DO go one sale like, once a year.
contrary to your belief though, nintendo DOES permanently slah the price of thier games.... around the last couple of years of the console's lifespan, as nintendo selects.
The difference here is timescale.
there is usually no real direct competition to a nintendo game, so both you and nintendo know you are going to buy it eventually.
meanwhile with other games thats not a mostly guarentee'd thing. and new games get forgotten by 6 months down the line.
meanwhile nintendo continues to promote thier earliest titles at full price well into the latter half of the system's lifespan.
since you are going to buy it anyway, it just makes finantial sence to not lower price.