Why doesn't mainland China have street signs like these in Taiwan?

为什么中国大陆没有像台湾(地区)这种路牌(招牌)?



I noticed that mainland Chinese cities never have signs like these, but all of Taiwan's cities do.
 
我注意到中国大陆的城市从来没有这样的标志,但台湾(地区)的所有城市都有。