The long answer: We did have PayPal as an option with an earlier iteration of our software but had to ditch it because it caused more problems than it solved.
PayPal's API forces donors to leave the site to make a donation, then click a link on PayPal's site to get back to the site in order for their votes to be credited correctly.
As you can imagine, many people missed the link, resulting in "lost" votes that weren't credited correctly. It quickly became a nightmare for our contest administrators, especially the final moments of a contest when every vote counts. No credible software in the donate-to-vote fundraiser industry uses PayPal for this reason.
Stripe (https://stripe.com/) integrates seamlessly with our software. Setting up a Stripe account is very similar to setting up a PayPal account (takes only a few minutes online) and all donations are deposited directly into your bank account through Stripe.
Stripe's payment processing fees are also competitive with PayPal's fees (Stripe charges a flat 2.75% fee on each transactions versus PayPal's 2.9% + 30 cents on each transaction).