Vouchers, as we knew in a previous time of Transport Tycoon, are now replaced with "EXP Tokens". In this page you can read all about EXP Tokens and what they mean.
When doing jobs, you earn EXP Tokens rather than Vouchers Each EXP Token is worth 0.1 experience in its skill (see below) You can also turn the EXP Token directly into experience at a rate of 0.05 experience per EXP Token
The EXP Token cannot be traded with other players, to do this you need to convert it to "Bonus EXP" Each EXP Token can be converted to a Bonus EXP item. In order to do this quicker you could also press the left arrow when in the menu for the different exp token types, this will convert all at once.
You can, however, redeem the EXP Tokens instantly from your inventory M > Inventory > EXP Token (Job) > Redeem, this is however at a lower amount of EXP than Bonus EXP would give you.
When the "Bonus EXP" item is in your inventory, you will gain additional experience every time you normally gain experience. Each Bonus EXP item is equivalent to 0.1 experience. For every 0.1 experience you gain, a Bonus EXP item is consumed and you gain an additional 0.1 experience. This effect goes up to 10.0 experience at a time. (Meaning up to 100 Bonus EXP items can be consumed at once)
The Bonus EXP item can be put on the marketplace, allowing you to effectively sell the EXP Tokens you receive.
Why not just keep Vouchers?
Vouchers discouraged players from doing jobs, allowing them to complete many jobs by simply paying their way out of it. Never once setting foot in a job vehicle. EXP Tokens still keep the benefit of "paying for experience". EXP Tokens keeps trading healthy (with the Bonus EXP item.) Players now have the ability to get boosted EXP yields without having to sit idle for hours at the Grand Exchange. You still maintain the player trade profit aspect from the Vouchers.