People still want to use private labs and to be fair a lab is not made in one day and night , its cost a lot and the vents/tables are heavy weight so they take a long time to order and gangs wont give up their weight without a hefty tag, i feel like give something back either removing minigame refilling water or removing minigame from watering the table will help balance it out. The time saving cooking helps people come to public labs so this wouldn't kill labs. To prevent the constant raiding of island lab you could add more tables to the other exsisting labs (Chili, garbage, etc), example make them all 10 tables total and island 15 tables due to the need of a boat 90% of the time for island lab, or add more labs in the city, airplane scrap and below dcc bridge would be perfect naming a few areas, adding more labs helps balance out solo crims from gang crims and reduces chances of them getting robbed and makes crims intrested by learning how to defend/attack the lab which arguably is the most fun part of being crim.