Ozarks
What you'd actually want, in that kind of setup, is to hand the active owner of the business you just partnered with a big bag of cash, see that distributed into the flow of legitimate income from the business, and then have it returned to you as dividends or whatever on your ownership stake.
But in the show, the goal is to then book a bunch of fake expenses against the business. So:
1. Purchase ownership stake in a hotel, for cash. The cash doesn't need to be legitimate. Money is transferred from you to the active owner.
2. Book fraudulent expenses for the hotel, making it look like it's spent a lot more money than it really has. No actual money changes hands anywhere.
3. Now you have a piddling amount of legitimate money from the hotel, and a big bag of illegitimate cash that you still haven't laundered.
We've skipped the step where you hand the owner some of your illegitimate cash under the table and then the owner gives it back to you above the table, which is the part of money laundering that launders the money. If you want to embezzle from a running business while making your expenses look like business expenses, you can just do that; you don't need to start with a pile of illegitimate cash.
eg: Your (say) hotel | bar falsely inflates customer income and then spends the illegitimate cash (supposedly from customers that don't exist) on rennovation works and "new" carpets, plumbing, etc that don't exist - the shell trades companies (carpentry, plumbing, labor hire) can report that money as legitimate washed income from the hotel.
There are a number of variations of this.
Why would you want to complicate it more with the fake rennovation works? Especially when a hotel is so much easier. You can just put fake guests on the book. (Or report longer stays for your real guests.)
With the renovation business you have to somehow cook up bills for the “new” materials and the workforce. So many more things the authorities could check there and thus so many more chances to slip up and get caught.
The ideal here is to have many injection points that can be inflated to a degree that doesn't quite raise suspicion .. and fewer collection filters (fake plumbing businesses, etc) that each 'charge' several injection points for non existant work and pool money that's invoiced and trackable (from hotel to plumber).
Also, as noted by SilasX in a peer comment the books for the fake work can include higher than normal payments for "supplies" to cartel owned suppliers .. yet another (fake but) documented trail to explain income and profits.
As the pooled money grows larger it's increasingly better documented.
It's literally a full time occupation to generate a mountainous pyramid of a paper trail to "explain" a million or so a week.
You might note that this scheme doesn't involve you owning the hotel to any degree. You only need to own the plumbing business. That's the opposite of the situation on the show.
The work is billed by fake (or better, partially fake) contractors who do no work but charge for time, labor and supplies.
It's a funnel with many cash casual customer locations inflate their intake and spend the excess on illusionary busywork "performed" by the next tier in the pyramid.
The entire paper tiger is controlled by the same entity .. who likely firewall and partition sections away (eg: the part that Marty did in Ozark (I read the synopsis) would be the cash flow in and a good number of lower level shell companies that he indirectly controlled) from each other and only are connected in a legal way to the upper layers that have documentation for their inputs from below.
First, they haven't obfuscated that; it's not present at all.
Second, your first step is that your hotel falsely inflates customer income. Then you follow up with some pointless additional steps. But if you can falsely inflate customer income, your job as a money launderer is already done. There are no additional steps. Spending revenue from your company on spurious invoices from another company is how you'd pay a bribe, not launder money.
You might want to dwell on the bookkeeping scale required to soak up that volume in a diffuse manner and then "legitimitely" consolidate that upwards.
I'm with you that a sleepy rural hotel can't handle that.
However, charging fraudulent expenses to the same sleepy rural hotel can't fix that problem. (It aggravates it!) The hotel can't spend more money than it has. And if you can make it look like the hotel has enough money to suit your needs, your job is already done. Fake expenses don't help.
After a long time spent on various dramas related to this initial problem, the show addresses it by having Marty found a casino, which seems plausible.
As I understand the show, they were buying overpriced things from cartel-owned enterprises, and that step was getting the money laundered to the client.
It is specifically mentioned that Marty books expenses that he hasn't actually incurred, notionally buying things that he never receives, which will stand up to an audit much more poorly than "buying overpriced things from cartel-owned enterprises" would.
The difference between $YYY and $Y is money that was claimed to change hands, but never did, and the difference between XXX and X is carpeting that Marty has recorded himself purchasing, but not actually purchased.
If he was buying the carpeting from a cartel-owned supplier, he'd just pay the inflated prices that he's so proud of booking without paying. Instead, he's buying real services from a real third party, and then booking fake expenses for unclear reasons.