The enemy had the advantage of speed, and they pushed this advantage to its limit.
So what advantage did Spark Squad have? Spark Squad had no advantage.
Spark Squad was just a small Expeditionary Army unit of a dozen or so people. They had traveled long distances, were short-handed, and under-equipped. In the battle against the Sanitation Workers, they had no advantage to speak of.
If this had been a normal war, then what Gao Yuan and his team were doing would have been suicidal, but this was not a normal war, so Gao Yuan and his team had no choice but to charge headfirst into the Sanitation Workers' defenses.
Now the enemy had shown up with six assault vehicles, but there were definitely more than just six assault vehicles.
The tactics of the Sanitation Workers were very clear—they were using a weakened version of leapfrog tactics, only they replaced helicopters usually required for such tactics with assault vehicles.