It gets easier to kill a lot of people when you have a lot more people to kill. Texas has 4-6 times the population of Spain 1400-1800. I mean, there is a reason you hear sayings like "I'll Believe Corporations Are People When Texas Executes One". This will stick with Texas for a long time.
The Inquisition operated in the Spanish Empire as well, but in any case, the point is moot. 12 people per year, on average, were executed by the Inquisition. It was not the bloodbath that anti-Catholic propaganda pretends it is. If Texas killed 60 people per year, we would not make it out to be some appalling example of state-sanctioned mass murder. Neither is the Inquisition.