Problems are:

It's a dry area to begin with
The drought isn't helping
The area is too big to patrol
The fires are usually started by firebugs or idiots throwing cigarette butts from cars... Can't monitor every person and fines aftercthe fact don't help ...(perpetrators are seldom caught anyhow)
Sometimes the fires are started by inanimate objects (prisms or other objects such as dangling ornaments , wind chimes, crystal balls etc which create a magnifying glass type effect of concentrating light in one spot) ...again can't be monitored

Biggest problem of all in desert areas:
Poorly underfunded fire fighter resources
Usually volunteers only

For example where I live in California desert we have the LARGEST area of sq miles in the USA for one fire division. It's entirely volunteer run ..mostly retirees... And NO funding !!!
Our firehouse is a toolshed and barely 2 men can stand inside it . It's tiny.
We are in extreme desert so there's really no plant life to catch fire... It's pure sand and salt out here. But if someone's house catches fire.. the team just stand there and watch it burn down..( if they even make it to the right place because there's no real address system many roads have no names.)

They will go in to pull any humans out ... But they don't have any proper resources to stop the fire  
So really they just do rescues.
Everything just burns.

Our taxes go to find stealing oil and poppies overseas but we can't even get a firehouse.
It makes my blood boil.
This country needs to start LOOKING AFTER ITS SELF FIRST

By putting out fires that should have been left to burn years ago we make todays fires bigger and more dangerous. Then we build nassive developments in areas that have long histories of wild fires.

Just follow the money.