Ah, you got me! I know the Roman alphabet, but I know only a few letters from the Greek alphabet, a few I picked up in math and physics. When I type in math, say, into TeX, sometimes I use some Greek letters, but I use only the ones that I am familiar with and, e.g., know how to pronounce! :-)
I mean, an alphabet is a huge step forward over freeform pictures, but the Roman alphabet offers basically nothing over its immediate ancestor the Greek alphabet except being a little better suited to ancient Latin.