The main solutions we have today are IP ban + VPN blocking using a database of known VPN subnets and adding them all to the firewall, and a similar fingerprinting technique which scans their folder structure of certain system folders.
Is latency going to be good enough on mobile data (especially if they're also using proxies) for a FPS, though? Sure, they're using cheating software, but I wouldn't be surprised if the software gets the information it needs to cheat too late often enough for it to be useful.
Even for non-obvious use-cases, it's hard to beat the advantage provided by knowing the position of players.
On my own hotspot, I have less than 30ms of latency.
Regular IPs can post freely
VPN or mobile IPs (blacklisted) must pay for a key ($20/year) that allows posting from blacklisted IPs. Key is good for posting from one blacklisted IP, locked for 30 minutes, so users cannot share keys. That way, you can ban the user by their key, if their IP is public.
It's not a perfect solution but it seems to be the best they've found for such a situation so far.
Sophisticated cheats in games like CSGO (and other competitive shooters) are usually very subtle, such as displaying enemies on the mini-map when they shouldn't be visible which provides a major advantage without requiring superhuman input, and the added latency is often negligible—especially when the info can be relayed to teammates and now you essentially have the entire team cheating with only 1 player suffering from a bit of increased latency.
And I wouldn't say this is an edge case either as in my experience the majority of cheaters I encountered are individuals that play on an alt account and offer a service to guarantee wins in ranked games.
I got to Supreme (2nd highest rank) with 150 ms ping. The people I queued with hit Global.
It's possible to play legitimately with very high ping. The higher ping put us at a disadvantage, but the skill gap between regions made it worth it to arbitrage.
EDIT: Well, I guess the tribe has spoken. Pretty surprising. I think y'all are just assuming you'll always be the ones with the "good" IPs...
In practice this means at lower ranks, it was not at all uncommon to be matched with players with similar rank but vastly better skills.
What do they do in such cases?
Assuming they get the report after the fact and assuming their "no logging" promises are true, can they even do anything? They're not even supposed to know which customer did it, after all.
If their promises are false, wouldn't they reveal their hand if they handed logs over willy nilly?
On some Japanese BBSes, spammers tend to use non-Japanese IPs or data center IPs. A good chunk of the spam goes away by blocking non-Japan IPs (easy to do with BGP data) and disallowing data center IPs (these often host VPNs, scrapers, etc.) from posting.
Posting from overseas thus costs money or is not possible. The trade-off is 1-100 extra users or significantly reduced spam for little effort. It's not surprising that most website operators choose the latter.
I also know of a file uploader that recently had to block overseas IPs due to such IPs repeatedly uploading illegal content. This is an example of a few bad actors ruining things for everyone.
It's basically impossible to keep one's rank at Supreme if you only play against Gold Nova or so due to the way the rating system works.
Blocking IP ranges by country or ISP is pretty much always going to have to exist as long as certain countries and ISPs turn a blind eye to abuse.
Even with as poor a solution as IP blocks are, it's the best we have and alternatives seem worse.
Anyway, it's a tradeoff between dealing with bad actors effectively and not impacting common users. There's a lot more bad actors than common users running into those sorts of IP bans though.