twest Nobody is out there offering a VPS server with free (legitimate) cpanel/plesk/da license. That would be immensely stupid to do. Everyone sells the licenses separately.
Not the case, people should take care making such claims. There are many offering inclusive licences. Of course, there are differences as to what makes business sense vs actual offerings.
As the OP refers to VDS which some would argue are more aligned to full dedicated, essentially, it doesn't matter too much with cPanel's pricing. And with that, there are several well established providers offering dedicated servers with free/included cPanel licences with no account limit. (These are legit and confirmed via the cPanel verify tool.)
They will do either on the basis that yes, they'll get some people who load up servers to stupid degrees but the average number of servers will contain an average number of accounts.
After all, the licence holder can see what their whole estate is doing and based on what they've charged and what the existing licence holders are consuming, could be an easy money maker.
This is no different to unlimited anything; bandwidth on servers, disk on backup services, food at a buffet. You'll always get someone that takes the piss but largely, it'll average out with all the normal use customers.
However, I hate to agree with cPanel, as I have a huge hate for them, the market changed. Server performance changed. Charging someone the same for a clapped out four core server with 16GB vs a 96 core server with 256GB ram, just wasn't fair. I'm purposely ignoring that they simply wanted a bigger slice of the profit pie (don't get me started on WHMCS pulling the same move)
For the OP: Enhance fees are reasonable, reward growth and have no base charge unlike cPanel. So you can have one server with one account and pay pennies. With cPanel, one server with one account, is still a hefty $ cost.
Simply, there are a lot of free or one-time control panel options but YMMV and you may find, over time, you'll have to chop and change. Direct Admin have flat monthly cost similar to what cPanel used to do so if you are cost sensitive and want a fixed cost for your product, that would be a worth choice - but - it is based on a single server implementation (like cPanel).