Are RC snubbers needed in this kind of use case for safety?
Well, when the relay switch contact breaks, current (of inductive load storing the inductive energy) has no where to go and therefore crazily fly across the contacts of the relay switch, in the form of a spark. The sparks would shorten the life of the silver contact points of the relay switch. But there is usually little safety problem (too little heat energy to cause a fire etc).
However, EMI (Electro Magnetic Inference) comes with the spark and may cause two things to happen.
EMI might cause flickers in your TV or HiFi equipment.
If you don't have optoisolation in your relay module (not the relay switch), EMI might be picked up by the signal/power/ground wires (which act like antennas) and triggers your Rpi to reset (usually won't hurt or kill your Rpi).
Back EMF is different from EMI. Back EMF is generated at the solenoid coil when the switching device, usually a power switching transistor, cutting off the coil activating current. This time the current has somewhere to go, through the flyback diode, or if no flyback diode, go back, in reverse direction, to the driving circuit, crazily killing things in their journey.
Back EMF can be suppressed by a flyback diode.
EMI can be suppressed by a RC snubber.
If you don't mind the EMI causing flicker in your TV set, or your Rpi from time to time automatically resets itself, then no snubber is necessary. Otherwise use snubber.
This snubber thing is electrical engineering stuff and you need to ask the EE guys for more details. You might like to read the articles at the appendix below. I googled those articles mostly from EE Stack Exchange.
Here are two pictures of MOV (Metal Oxide Varistor, snubber) for you reference. I bought the quad relay green module with preinstalled varistors from a industrial products shop, not from eBay who sell you cheapy relays! :)
Appendix - AC EMI References
Introduction to Transient Voltage Suppressors
Mechanical Relay Primer Section4.3.1 Arc Supression
Simple relay circuit getting noise spike form AC line - ETech online 2009apr05
Relay noise problem although flyback diode is used - rudwna 2015may24