Why airplanes taxi

So, logically, spacecraft in the frictionless environment of outer space
should immediately accelerate to the speed of light.


Some haphazard math here.. if space is indeed entirely frictionless,
which I highly doubt, then to accelerate a body of weight 1kg (2.2
lbs) to the speed of light (using a constant force of 1N (or 1 m/sec2
acceleration) would require a distance of 4.5*(10^16) meters or about
45000000000000 km which is about 300 billion miles. The work done/
energy needed would be about 450 trillion joules.
The time needed to achieve this feat would be about 9.5 yrs.. so no
its not instantaneous