Recording songs on your computer for replay - against the law?

Remember the old days of recording music off the radio and playing it over and over? Remember when they invented the radio and duel cassette deck all in one so you didn’t get background noise when you recorded the music?
Isn’t recording a song using wav software or windows software the same thing? That was legal then, so why shouln’t it be legal or acceptable now?
(not to be confused with KaaZa or any other song sharing software-I dont /won’t do that.)