IMHO it's not a difference between courses and production, but rather about the difference between preprocessing needs of different NLP ML approaches.
For some of NLP methods all the extra preprocessing steps were absolutely crucial (and took most of the time in production) and for other NLP methods they are of limited benefit and even harmful - and it's just that in older courses (and many production environments still!) the former methods are used, so the preprocessing needs to be discussed, but if you're using a BERT-like system, then BERT (or something similar) and its subword tokenization effectively becomes your preprocessing stage.
For some of NLP methods all the extra preprocessing steps were absolutely crucial (and took most of the time in production) and for other NLP methods they are of limited benefit and even harmful - and it's just that in older courses (and many production environments still!) the former methods are used, so the preprocessing needs to be discussed, but if you're using a BERT-like system, then BERT (or something similar) and its subword tokenization effectively becomes your preprocessing stage.