RS422/RS485 termination and noise immunity
You can have a bus where a single RS422 transmitter drives many receivers, so the termination must be only at the last node, and other nodes must not have a termination. Omitting the termination from the board gives the opportunity to wire the boards on the bus as you like and terminate the bus separately. It also allows the termination resistor to be selected based on bus impedance, e.g. 100 ohm or 120 ohm. If the bus is short and data rate is low it may work fine without termination, so you have the option also not to terminate. In your case there environment is noisy so termination is a good idea to keep low and balanced bus impedance.
The pull-ups and downs are there to keep a default receiver state if it is disconnected from bus, sometimes this feature is built in to chips.