Nearly all non-south Indian scripts have the line above the letters, Gujarati has no line and its the only one without the line. What caused this?

It's more conveniant not to make the line, maybe? Hehe, don't know how to write it really, my mom tried teaching me it when I was like 10, but I kinda gave up.

Read up on it a lil more and I think some Jain monks started to write without the line because they associated the Sankrit based script with the priestly oppresion of the Brahmins. Also Gujarati is supposedly heavily influenced by Persian and Arabic so maybe that might have something to do with it also.