I believe what he means is why do we have no surface-level photos - IE, why haven't we sent a lander or rover probe/craft to Mercury, only orbiters and flybys?
The reason is because Mercury has basically no atmosphere to slow a spacefaring vehicle down upon atmospheric entry. The surface temperatures also fluxuate wildly because of this.
The only option you'd have for a safe landing is a propulsion system powerful enough to completely cancel out the velocity of your spacefaring vehicle. The amount of thrust you'd need to generate (and fuel needed for that) is extremely cost-prohibitive and impractical. And then your equipment would either be unsuitable for the heat of mercury or unsuitable for the cold of mercury.