
Quoting
Speedy Gonzalez
It appears to be less than 200 feet between the end of the merge gore point and the beginning of the left turn lane. You must have had at least that much distance to have legally changed two lanes to the left, which is likely why the sign exists (that and the mention of possible accidents in that location in the past). Is the sign in a shitty spot? Yup. Does it suck that it was put that far back up the road? Yup. But, you missing the sign doesn't constitute a defense to having disobeyed a regulatory sign.
The reason there is no other sign is because it is legal for traffic traveling West on Ecorse Road to turn left at Inkster Road.