Tarkov like most games uses client side prediction with some server side checks on actions, it can be hard to see the difference between a predicted action and client authority, they've been slowly increasing checks over the years as cheat developers finds new things to exploit. Since checks can be costly for performance you don't want to check things you don't have to, so doing it incrementally as you need is ok, for a game that is in a heavy development stage.

Unfortunately they are not doing lazy loading of loose loot and containers (including player/scav), so ESP is extra powerful in this game. But since Tarkov has complex maps there's little point in trying to hide players that are not visible, CSGO and Valorant are the only FPS games that does this but they also have simple and small maps with fewer players. So player-ESP and aimbot will most likely always be possible as long as you can bypass Battleye, so instead of cheaters rushing for loot they can see you might just go and kill you.