The translators put in a lot of amount of time, eg clean-up of the art and overlay. Also it depends on the translators interest in the manga. If no one is interested, it doesn't get translated. Second, it also requires fluency in the language. Less fluent translator, the poorer the translation. In addition, it also requires some knowledge and skill with use of graphics tools otherwise the text and art stuff doesn't look right or flow. Some of the non digital ones eg manga require severe clean-up from scans as well as errors check for typos and what not. It's not a one to one conversion. Hence, that's why it takes awhile. Everyone takes things for granted that there will be a lot of free manga. Yeah right, be thankful.