If you are located in the US, most states have adopted the Federal Motor Carrier Safety Administration Cargo Securement Rules.
Skid steer loaders under 10,000 lbs are secured the same as automobiles:
Securement of automobiles, light trucks, and vans.
Automobiles, light trucks, and vans must be restrained at both the front and rear to prevent lateral, forward, rearward, and vertical movement using a minimum of two tiedowns.
Tiedowns that are designed to be affixed to the structure of the automobile, light truck, or van must use the mounting points on those vehicles that have been specifically designed for that purpose.
You are also required to secure any articulating parts and accessory equipment (loader arms, backhoe arms, booms).
MnDOT requires a minimum of three tie-downs on skid steers: rear of loader, front of loader, and boom/bucket. I still see many skid steers on trailers that do not meet minimum securement standards. MnDOT Commercial Vehicles Division conducted a training seminar at my Bobcat dealer. They covered all the rules and requirements pertaining to trailering skid steers and small excavators. It was very informative.
In summary it is all about safety. Many drivers think nothing about loading a $20,000+ piece of equipment on a $2500 trailer and don't want to spend the $100 on chains and binders or spend the time to secure it properly.
It would really suck to loose the loader off the trailer; worse would be to also total the truck; much worse would be to hurt someone else. Your court and medical costs will most likely be much higher than the total costs of your equipment.
If you want the exact requirements for your state, contact your Dept of Transportation. Fines for improperly secured cargo can be big bucks.