They ask for an airline ticket because there are no direct road or rail connections from morocco to Algeria (I THINK!!), so they take it you want to fly. Try asking at the embassy directly and explaining your problem. But they may insist you get it with an airline reservation or in the last country if you say you intend going overland by another route i.e. from France or Niger.
There used to be that thing going a few years ago where you needed an airline reservation to get a Mauri visa. You got a ticket from a travel agency, got the visa and then the travel agency cancelled the ticket, charging you between 10 and 25% of the ticket price. Not every travel agency did this, one of the few was opposite the central train station in Rabat.
The embassy is probably in Rabat, though there may be a consulate in Casa. If you think it's going to be difficult it may be worth trying the full monty at the start, i.e. shirt, tie, neat trousers, wash, shave, and maybe an introductory letter from your embassy. A lot of people laugh at this but I lived in Africa for years and dropped the "scruffy murphy" appearance when I had anything official to do, seemed to get things done a lot faster like this.
But remember there is no land route from Morocco to Algeria ( afaik), so flying may be your only option.