No prejudice involved, just passing on the story as I've heard it. Actually digging around a bit on the net, it sounds as if there's evidence that some scalping did occur even before the Europeans arrived on the scene.

Here's a quote from a site I found:

While Europeans did not originate scalping, they did encourage its spread through the establishment of bounties. J. C. B. writes that "the French and English were accustomed to pay for the scalps, to the amount of thirty francs' worth of trade goods. Their purpose was then to encourage the savages to take as many scalps as they could, and to know the number of the foe who had fallen."

The French paid virtually nothing for scalps, preferring to purchase prisoners that they would at times send back to their families or utilize for prisoner exchanges. Father Pierre Joseph Antonie Roubaud, missionary to the Abenaki at St. Francis, obtained a scalp from one of his warriors to redeem an infant from a Huron captor. The priest then reunited him with his parents.

The English, however, passed acts through their colonial assemblies. Even before war was declared, on June 12, 1755, Massachusetts Governor William Shirley offered £40 for Indian male scalps and £20 for female scalps. The following year, on April 14, Pennsylvania Governor Robert Hunter Morris "declared war and proclaimed a general bounty for Indian enemy prisoners and for scalps." The bounties to be paid were £130 for a male scalp and £50 for a female scalp.

J. C. B. also mentioned that "to increase the compensation received for scalps, they got the idea of making them of horsehide, which they prepared in the same way as human scalps. The discovery of this fraud was the reason they were more carefully inspected before a payment was made."