Parents not being parents

This is ridiculous. [Link]

Every now and then, we see some news article or column breathlessly warning us of the over-sexualization of young girls. They talk about media influences, pop stars who ooze tons of sex and very little talent, stores selling clothing more suitable for strippers than for seven-year-olds, toys and dolls that sell looks and image, magazines for women and now teenagers as well that scream sex at the checkout counter for every single grocery store you go to... the list goes on and on. They warn of how these things are having tragic effects on our young girls and teenagers, and how the market needs to change.

Today, I came across yet another one of these articles with this opener:

Thong panties for 7-year olds and padded bras for girls as young as nine are among the items many parents are purchasing at local stores.

The sexualization of girls is blamed mainly on media; music videos, magazine covers and the like.

How does a parent get the idea that buying those for a preteen is appropriate? I can't picture when buying a thong for a daughter would ever be appropriate. Again, where does this idea that this is appropriate come from? Where?