When strata managers are left to source tradies themselves, this inevitably leads to suspicions (usually unwarranted) they they are in cahoots, getting kickbacks from inflated charges. That’s why they are asked to source three quotes.
Part of the strata manager’s duty of care is to make sure the tradie is qualified, licensed and insured. That takes time and therefore has a cost attached.
Most strata manager have a list of reputable tradies that they know are fully licensed and insured. The downside is that there may be good people not on that list.
However, if you and your committee cohorts aren’t even sure how to find tradies in the first place, how likely are you to be able to do those due diligence checks and how likely is your research to be accurate?
Perhaps you should start by contacting the strata committees in other blocks and ask who they used and how they worked out. Or just google the trade you require alonside the word “strata” and see what that turns up.