No Spool function in MP3s

But what not even came up is a shortcoming that I absolutely can not understand.

Within an MP3 file, regardless of whether this is on a USB stick or a burned CD (both of which are recognized without problems and play)
is possible not forward or rewind.
Ie. at a 60-minute MP3 (music mix or audiobook etc -beides I hear regularly) I can hear every time without having the opportunity to fast forward to Minute20 from the outset.
With audio CDs this works without problems.

For me, it therefore makes no sense.
a real shame!
Even my 6 year old car radio can something.

Goods returns.

PS Amazon as always excellent!