A great thing about Debian is that it welcomes anyone to become a volunteer on the project. As a result, it has over 900 developers and over 10,000 packages available.
Scala is not yet packaged for Debian. Every time I think, "all I need to do is tar up some files", I run into a discussion like this one. While Debian developers are welcoming, they are also extremely nitpicky!
In this particular case, I actually think that LAMP's release of Scala should be a "native package", as Debian calls it, which means that the source code for the Debian package is the exactly, bit-for-bit the same as the source code of the "upstream" package. That is in fact how the planned distribution would work: at the same time a LAMP release of Scala happens, there would be Debian packages created out of the same source tree. Bit for bit.
However, many experienced Debian developers seem extremely opposed to native packages, so I keep revisiting the decision. The result is that nothing happens at all. I have to wonder: is this really a big deal? The use cases cited in the above seem relatively unimportant when you consider that the absolute worst case is that someone does a diff themselves and observes that it is, in fact, empty.
Debian would be better if it had a way to upload non-nitpicked packages, especially to its unstable branch. Insisting on policy perfection before even uploading the first version means that it takes a long time to get the first version out. It is as if many Debian enthusiasts would rather talk about packages than actually build, distribute, and use packages.
As it is, Debian users who want Scala will simply have to use a generic installer.