Unions are bad for job hopping, which is the current method for the dev side. They get good pay and benefits, and generally get stock as part of compensation. The stock is anathema to US Unions which operate in a hostile manner to the companies. The stock is also how a lot of devs have had very good paydays. A software dev union probably looks more like a guild.
On the running cables side of IT, unions do exist. Especially on the ISP side. The IBEW appears to actually help their members more so than say UAW, so if you are doing this work, they might be able to help you unionize if you want that.