According to CL (dnoyeB) Gilbert :
This is odd, could you explain that to me? I am an automotive systems
engineer and I design the wiring for automobiles. The length of wire
has nothing to do with the fuse rating. The device on the end of the
wire also has nothing to do with the fuse rating.

Well ok, some devices can terminate a few different sizes of wire, and
this is a physical thing, nothing to do with current amount but with
diameter, etc.

So why does wire length matter for breaker size in a home?

It doesn't matter directly, but there are some indirect effects.

First of all, and this applies to your engineering, the fuse/breaker
should be no larger than the current carrying capacity of the wire.

Second of all, in AC power wiring, devices are tested and approved
for connection to a maximum circuit ampacity. So, you can't put a
15A 120V device on a 60A circuit.

And thirdly, which is where wire length comes into play: certain
devices (especially A/Cs and other large motor-powered devices) have
very large startup surges. The wiring has to be large enough so
that coupled with wire length, there isn't excessive voltage drop to
the device. The more the voltage drops, the more the startup surge
is prolonged. Coupled with the fact that breakers and fuses have
time-delay factors built in, it's entirely possible for a large
startup motor load (like a central A/C) to trip a breaker on 100' of
wire when it wouldn't trip the breaker on 10' of the _same_ wire.

Often the wire size has to be a size or two larger than the ampacity
would dictate to reduce voltage drop. With A/Cs and certain other
loads, not only the wire sometimes has to be larger than you'd expect
(with long runs), the breaker has to be somewhat larger than the
steady-state draw of the A/C would suggest.

Central A/Cs often have somewhat oversize wires and breakers, with
a fuse local to the device closer to the A/C's continuous draw.

--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.