Why waste time...IMHO, the veneration of Mary is nothing more than a closet form of worshiping a dead person, and building roadside shires to that person nothing more than idolatry-pure and simple. Shrines are an object of religious worship and pilgrimage. They are sinful and in complete disobedience to God's laws. If you want to trace this to tradition I would suggest looking in the Old Testament where people were prone to worship "the temple" and the "high places". As for Mary, the book of Jeremiah tells us where the people were prone to pray to the "Queen of Heaven". Instead of posting shrines to Mary, it be more appropriate to post reminders of Christ. Everyone has their priority who they wish to remind people of and desiring to emphasize Mary over Christ is telling to say the least.
While I appreciate my Catholic (and Orthodox) friends, I would suggest to them they are in grave error over this matter. The difference between Shinto and the Catholics is one doesn't profess to be Christian. What's the difference between traveling to Mecca or traveling to the shrine at the local bus stop to say a prayer? It is not my place to judge anyone (including Catholics and Orthodox) but it is my place to warn them. If I wasn't certain that this was in error I would say so. It is an error and if this sounds "anti-Catholic" so be it.
I hope I'm a bit clearer on my position.