CAS command question

[compsystems]

What is the reason for "reverse" expression (transposing terms and reverse the operator)? (some help for the parser or interpreter of expressions), in my case I do not like as the hp-prime shows, books do not show this notation, is somewhat confusing for to read.
(x+y)< 4 →
4>(x+y)

Examples of how to use the command LEFT & RIGHT

PHP Code:

// simplify none
#cas
  
  testleftcas():=
  begin
   local expr1;
    //local expr1:='(x+y)<4';  =(
    expr1:='(x+y)<4'  
    return([ left(expr1), left(eval(expr1)) ]);
  end;
  // testleftcas() -> [ x+y, 4 ] // ok

  testleftcas2(expr2):=
  begin
    return [ left(expr2), left(eval(expr2)) ];
  end;
  // testleftcas2( '(x+y)<4' ) -> [ x+y, 4 ] // ok
  // testleftcas2( (x+y)<4 ) -> [ 4, 4 ]    // ok

  testcas( id0 ):=
  begin
    local id1:= id0;
    print; //print("");
    print( [ left(id1), right(id1) ] ); wait;
    return ( [ left(id1), right(id1) ] );
  end;
  // testcas( (x+y)^(1+1)-3 ) -> [(x+y)^2,-3] // ok
  // testcas( '(x+y)^(1+1)-3' ) -> [(x+y)^(1+1),-3] // ok

#end