The difference is . Squad and Take-Two own the 3D models, sound effects, and code for the DLCs. An unlocker circumvents that. While you might argue that "information wants to be free," the reality is that developers have families to feed.
: These tools intercept calls from games to digital storefronts (like Steam, Epic, or GOG) to "spoof" or emulate the ownership of DLC. DLL Injection
Kerbal Space Program goes on sale frequently. Historically, the complete edition (base game + both DLCs) drops to during Steam Summer/Winter sales. That is the price of a pizza. Setting a price alert on GG.deals or Isthereanydeal.com is safer than downloading a malicious executable.