There is a logic behind this, but you kinda have to be a linguistics nerd to know.
L and W are pretty similarly pronounced in many languages including English. Over time, this plus the fact that some might have difficulty speaking the language (still learning, have a lisp, low literacy, etc) leads to Ls becoming Ws in places.
Long story short, L took the L sometimes in English
Rules for thee but not for saymen (monyet.cc)