Isn’t your teacher lied to you ?
Isn’t your teacher beated you for no reason ?
Isn’t your teacher get angried to you without a proper reason ?
Isn’t your teacher used you and then didn’t minded you ?
Isn’t your teacher give too much punishments to you ?
Etc…
But still why ?
(Am not asking this to criticize anybody or disrespect others. Just a doubt formed in my mind as a student. If am asking anything wrong please correct me)
Courtesy should be an obligation, but acknowledgement shouldn’t have to be.