While there is a kind of classification for open-source licenses, the classifications don't really extend beyond open-source.
The best classification that I can come up with for the RSAL is that it is a source-available license that allows usages that don't compete with Redis Lab's business. But that classification of course only contains the one license.
Therefore, not having in an ...
Some security chips, you need to sign an NDA just to get the datasheet. Drivers you only get once you send the vendor your own public key for encryption. Just those NDAs might stop a company from publishing the source code - if that source would inadvertedly disclose details under an NDA.
There are a couple of moving parts here:
What is the justification for not opening their source code?
This is more of a question to the customers (in this case - the government) than the manufacturers. I don't know any specific details about any voting system, but generally speaking, if the government purchases anything (in this case - a voting system) ...