i’ve played games with a tax system and in reality most people do not mind as its usually a minuscule amount that its basically unnoticeable, individually its not a lot but as a group it can help out a fair bit. If a guild wants to put a high tax in thats there problem as people can make there own decision whether to join or not, there would be plenty of guilds with low or no tax at all.
The tax should only come from rewards and not market transactions