The shop I worked at has their own plating department. Nickel, Cadmium, anodizing, but no chrome. Like Occupant stated, polishing is a very tedious job. Anything missed in polishing will most likely show up in plating.
A few years back, we were going to move from our old plant into the newer plant. To move the plating department was over a million dollars just by itself. They decided to leave manufacturing in the old plant. Now mind you that over the years they went from having some metal tanks to all poly tanks, composite grids in the floors, a wastewater treatment department and other items. They had to put a huge filtered vacuum system in to pull out the fumes from the department but could not release any toxic chemicals in the air. It was close to $500,000 to upgrade more than what had been upgraded. Also, if ANYTHING, and I mean ANYTHING, chemical wise would make it to the local sewer system, there will be HUGE fines.
A few years back, someone from the cleaning company dumped a mop bucket of water in the sink. The way they found out was fine bits of grit and some metal shavings. In a week we had a complete new cleaning company in with very strict warnings about anything dumped in the sinks. Anything like that now had to be classified as hazardous all for the fact that there may be Beryllium Copper shavings, spilled coolant where parts were taken out of the machines, and a multitude of other things. So any mop water, water trays from a grinder, old coolant being replaced in machines, now go into 55 gallon drums clearly marked HAZARDOUS.
So a plating facility that does nothing but plating have expensive permits, and real hefty fines. Our plating department is relatively small compared to places that plating is their soul business. They have to charge for all of the chemicals, the chemicals have to be routinely switched out now, and depending on the company, the larger the company, the more barrels of hazardous waste they will have. Companies have come a long way with reclaiming a lot of the chemicals, but for the most part a tanker truck comes in and will pump out all of the storage barrels and plating tanks or the chemical recycling department. Most companies don't want the hassle of having to certify their own drivers to carry hazardous waste somewhere, so they hire companies that are specifically designed to do that. And again, at a large cost to the plating company.