Because

a) floats inherently leak over time unless they are some light solid, and
then they have a tendency over decades to break down and saturate.

b) the "state of the art" for float sensors use a wiper against a nichrome
wirewound resistor and the wiper tends to wear a hole and the nichrome tends
to redistribute itself across the form somewhat nonlinearily.

c) just because it was good enough for Henry Ford, it's good enough for us
{;-)


Jim



All of them good ideas, but why are they likely to be more accurate
than the float level sensor?