Potential bug(?): Inconsistent usage of column() / col() and literal() / lit()

[HeWhoHeWho]

Describe the bug
I couldn't locate the exact documentation that lays out the usage of column() / col() and literal() / lit(). Here's what I encountered, I will start describing the problem for column() followed by literal():

• column() / col()
  .select('id') -> worked as intended
  .drop('id') -> worked as intended
  .sort('id') -> didn't work -> AttributeError: 'str' object has no attribute 'expr' I had to fix it with .sort(col('id'))
.filter(col('id') > 123) -> worked as intended
  .with_columns(ID_students = F.when(col('id') > 123, lit('Good')).end()) -> worked as intended

• literal() / lit()
  < removed > Found the answer myself

To Reproduce
Steps to reproduce the behavior: You may use the codes above the reproduce the inconsistency mentioned.

Expected behavior
I'm speaking from my experience with Polars - which is also built on Rust.

For col(), I expect that col() is not required for select, drop and sort operations, except for filter and with_columns. There may be more operations out there that I am not aware of that may not need col() to work. In Polars, .sort('id') works right off the bat.

P.S. I made reference to Polars as their syntax are very similar to each other. Please let me know if I shouldn't be viewing from Polars' perspective due to something crucial between the two packages that I am not aware of. Thanks.

Additional context
Just wish to understand the usage of column() better so that I don't have to guess when and when not to use them.

My data are stored in CSV file if that matters.