Not a lawyer but maybe there’s a few possible reasons:
Standing: without a reason that looks remotely viable, a court might just throw it out without requiring a defence.
Risk: big companies have legal departments on hand to make your life hell for even trying.
Reward: smaller companies don’t have enough money to be worth your time to sue. Even if you’re trying to “send a message” the first attempt is so expensive for no gain, it’s not worth your while.
Government departments tend to fall into a bad middle ground. There’s enough money to be worth fighting over but they’re not always fantastically well equipped to defend it (or at least they’re perceived as such).
Standing: without a reason that looks remotely viable, a court might just throw it out without requiring a defence.
Risk: big companies have legal departments on hand to make your life hell for even trying.
Reward: smaller companies don’t have enough money to be worth your time to sue. Even if you’re trying to “send a message” the first attempt is so expensive for no gain, it’s not worth your while.
Government departments tend to fall into a bad middle ground. There’s enough money to be worth fighting over but they’re not always fantastically well equipped to defend it (or at least they’re perceived as such).