Too infested with the jiu hu FTs, combined with a high Sinkie cost of living.
Also, there's really nothing in Woodlands. It is nothing more than an industrial shithole. Even people who live in the north are reluctant to work there, if given a choice. To get to the nearest places of civilization, you'll have to either go to Yishun or the Bukit Batok-Choa Chu Kang area.