I’ve got a question with laser weapons in 5e

So i understand when using range weapons such as bows, cross bows, and firearms such as rifles we add our dex modifier to the damage roll. Does this apply to laser weapons such as laser pistols and laser rifles? Our dm informed me because they are a special property they do not add the dex modifier so i just rolled with it but by pure curiosity i want to know the reality. I don’t mind if this is a house rule to not add the dex modifier but i just got curious with the RAW rules

The Futuristic Items don't behave differently than other ranged weapons so they add Dexterity modifier as usual.

Thank you for the reply

Thank you for the reply i just wanted to know the raw rules and by your help i was able to know