Why do we have to pay extra to use our debit cards?

I was a carpenter my whole life and now I am a drafter. In order for me to do my job I must buy tools with my own money. Hammers, saws. pry bars, now it's software, computers, printers, ink. How in the hell has it become legal for a merchant to charge me ....and every person who shops there....an extra charge to use a debit card? It is a tool or them to make money....why do WE have to pay for that tool.....over and over and over again.

Ordinary Guy2014-07-19T10:52:29Z

Debit card costs 15 cent per use typically. The user pays not the merchant. A credit card costs the seller 1-3% of sales price. The merchant pays not the user,