Freight owners frequently call my cell phone, asking me where I am running now and pressuring me to quickly transport goods.

Typical exploitation resulting from the "market reforms" of a few years back. The government needs to turn its "guidelines" on drivers' sleep hours, etc. into legally binding regulations and severely punish violators, and the drivers need to be allowed to form unions and take collective action to protect their rights.

My brother-in-law is a truck driver in Tohoku. His shifts are 15 hours on the road.

In the US, drivers aren't allowed to work shifts longer than 14 hours, and only 11 of those hours can be spent driving.*

Yes, I know this isn't the US. I'm just sayin'.

Over 80% of Japan's transportation firms violated overtime and other labor rules.

A survey found that some truck drivers were on duty for about 320 hours per month, exceeding the basic upper limit of 293 hours set by the government.

European drivers' hours are recorded on tachographs. Exceed your limit and both you and your company are in (expensive) trouble. Customs officers or the police will impound your vehicle and everything in it, and make your boss send a fresh driver.

Some companies were using software to allow customers to GPS track couriers on google maps, so they would know when their parcel was about to be delivered. I haven't seen so much of that recently. Perhaps it made the courier too easy a target for criminals to rob. It usefully allowed people to go to the toilet knowing that the courier was at least a few deliveries away from hammering on their door.

If harassed, turn your phone off (or purchase two and use one to call the other for periods when you are being pestered, so the line is 'busy'). They will switch to bugging your company instead.

Just criminal and human exploitation

Instead ask for technological progress.

Don't answer the phone. I'm pretty sure they're not going to fire you while you are delivering their precious cargo. "I did not answer because I could get a ticket for talking on the phone while driving, further delaying the shipment."

The fitting answer is, if you brainless creature wouldn’t disturb and interrupt me, all the goods would already have timely delivered to your company. Don’t just call next time to get it quicker.

Don't answer the phone. I'm pretty sure they're not going to fire you while you are delivering their precious cargo. 

Because being fired after the delivery is done solves the problem?

This is a recipe for disaster, sooner or later a tired driver is going to cause an accident so huge that there will be no way to hide it was caused by the completely inappropriate work conditions prevalent now.