Allow me to share my point of view in this scenario.

P.s if thread starter doesnt like it, i will edit it

Firstly, most wont tint the front windscreen because , most windscreen comes with double layer nowadays so actually it isnt necessary for it to tint front windscreen .

Secondly, purpose of this security tint is actually to those who want to break into your car to take your bag or etc.. How many times have u seen ppl trying to brake into your car through the front glass

Thirdly, due to the thickness of the tint, and especially if your front glass is very uneven i mean, curve, it wouldnt be an easy task tinting the front windscreen.

Bout why not the rear window?

IMHO, first maybe because of the package price, maybe by this way, this package would be more affordable to everyone but i am sure, if you guys want to tint the rear u guys can always request for it, aka pricing wise u got to ask lo of course, fair enough.

Second might be, again, due to the curve of the glass.

Just my opinion, do correct me if i am wrong

p.s but it would be proper for ms canny to state it in her post about the 4 window, so that ppl are aware of it . Cheers