WCFM Shipping by Distance Rate

Hello!

I am trying to enable the shipping by distance rate on WCFM, but I have noticed that the actual KMs are not accurate. I put the actual address on google, and the distance is calculated to be 3.9 km, but when I set a rule for example More than 3.8 it is not giving me the correct quote.

It seems to me that WCFM Shipping by distance rate uses a straight line in shipping, and not the actual navigation routes from Google API. Can someone please confirm this?