1. A fair price is a price that two parties agree to assuming no duress caused by the other party
2. A fairer price is one where one party didn't gain an unfair advantage through a monopoly or failure of a free market - real-estate agents inserting themselves in a transaction, monopolists, government intervention..
3. Fairer is a price where the buyer and seller offer the same price to anyone
4. Fairer is when both parties know what information the other has
5. Fairer is when both parties have similar bargaining power and neither party is sticky, i.e. has a significant preference to buy from the other party - company store, specialized workers with only one employer (NHL, NFL etc), renters already in a unit.
6. Fairer still is when both parties have the same information
Ideally we always have the first 5 and at least some parity on the last. The less fair a market is, the less efficient it becomes. Item 4 actually helps both parties by reducing uncertainty by the buy and increasing the price for the seller.
I'm wary of supporting bills like this because governments have a tendency to support policies that break these conditions of fairness and while they seem as if the policies would help "the little guy" in practice they often do the opposite. Rent controls and zoning regulations have been a horrible to younger people and have created most of the homeless problem in Canada (we regulated away flop houses, the housing of last resort). Rules on insurance have caused insurance companies to stop offering insurance. Regulatory burden has lead to regulatory capture in many industries and a huge barrier to entry in others. Unnecessary licensing drives up costs and restricts young workers from entering many trades. The track record of these laws is terrible. This one seems like more virtue signaling than anything else. No brick and mortar store will raise prices based on who you are, although they may have selective discounts. On line stores are already doing this but since their servers aren't in the jurisdiction I don't see how this will help. Finally, voluntary price discrimination is helpful. When I travel by air in the livestock section my flight is partially subsidized by the people paying 10x as much as me in first class. So we have more regulation but I'm not sure we are better off.