It depends on whether lacrosse is an "official" school sport or if it's technically a "club" sport. If it's an official school sport, as it is at most schools that have a lacrosse program (I've never heard of one where it's not) then the school is required by law to provide protective equipment to participants that do not have their own. It's different with club sports because they are technically not officially sanctioned by or connected to the school. For example, due to the high costs of equipment and ice time, hockey is a club sport at most public schools which means that the players (i.e. their parents) must pay for everything including, including all of the equipment, all ice time for practices and games, the coaches' salaries and the officials for each game. But as I mentioned, every high school lacrosse team that I've heard of is an official school team, so if you play for them they have to be able to provide all of the equipment that you need except for a stick, cleats, and probably a cup.
15+ years of playing and coaching lacrosse