Not everyone does, or really needs to. I've been in this business for 15+ years, taking only checks or cash (95% of the time checks) and don't think I've ever lost a prospective customer due to not taking credit cards.
I signed up for PayPal to do my credit cards. Now I'm stuck with taking cc's b/c my YP ad says I take them. However, I wish I hadn't b/c I've only had 2 people pay by cc. Paypal charges $20/month for the service, but it's easy to do and is all done on the net.
I make sure I tell the customer its cash or check.
If they ask why no cc, I just tell them it would make me have higher prices due to the processing fees and I would rather pass on the savings to you the customer.