Unfortunately, some very cruel things happen in this world, and there are maintenance companies you would never want to work for.
First of all, they do not SHOW what these people do to make this work, and they do not SHOW and adequately explain the support machinery and filters.
Unscrupulous maintenance companies: there are some who throw something together to meet contract, then come in a few days later at a very high maintenance fee to 'do the chemistry' and collect the bodies, replacing the dead with similar fish: back every week to do the same, and the fee is so high it covers the weekly dead fish that the owners never see. Those who treat fish as decorations don't care.
The TV show: remember that in these specific tanks there are processes that are edited out as unglamorous or 'slow'.
Note too the purposes for which some tanks are set up: there are some 'processes' that do not work longterm, ie, the tank is set up as a decoration that will be replaced in 6 months when the theme or attraction changes. Essentially what is being set up for these commercial operations, as described, is more on the level of a very large quarantine tank with sand, and probably with a UV filter, which will help keep disease down, but also kill off beneficial bacteria. The filtration these tanks on the show use is very likely similar to what we used in the 1980's, relying not on the rock (which is fake) but on filter pads, and on close monitoring of chemistry, probably some spendy automated systems that report their condition, or just a guy coming in every few days to run tests.
This is not a show you watch to learn from. Not as the producers are doing it. THey are making a lot of trouble, and they are going to kill a lot of fish, as people show up at Petco, buy fish and a tank and a box of salt and dechlorinator the same day and go home and put it together.
And if you're personally spending your time and money on a tank---you, the serious hobbyist, will want to follow a very different path, one that is designed for the long haul, not a quick display and equally quick breakdown. You have to cope with chemical cycles that progress into years, you have to design sandbed maintenance that doesn't disrupt; you have to plan for the rapid growth of marine species; you have to consider what happens to oxygenation as your fish need more, and have relatively less water; you have to plan for years, not weeks.