Why Does COX Charge %50 More For Internet that the rest of the world and it way slower

Cox does what they want and they dont care. Im on my 4th cable box in 2 month. I still have issues with all cox services. Voice and video is off by several seconds. Jumps back several seconds when it wants. Its just ** service

I hate cox, can't wait till more isp come to my area

To directly answer your question "Why", : 

because they have a monopoly on the wired ( as opposed to wireless ) signal distribution system in the municipalities in which they are authorized by local government to provide service.

This is a legacy of cable television, which was the only programming service in the era of its inception which required a bandwidth capacity remotely akin to what is now offered routinely by ISPs.

Government did not want / could not afford the cost of cable TV infrastructure construction.
Rather than encourage competition among service providers using an industry consortium financed infrastructure,
local government, in accord with federal regulatory impetus, pitted service providers in competition against one another to offer the greatest range of service in exchange for exclusive service provider rights.

Because that provider ( eg Cox )  owned the physical distribution network, the wires & amps on the utility poles, they paid to build, they de facto own the provider rights in perpetuity.
Municipal authority sunsetting that exclusive right or reclaiming the power to sell it portends so much uproar of protest regarding service disruption among the voting customer base that the sleeping dog of monopoly was let lay even until now, when that infrastructure, since heavily upgraded for the purpose, remains the only distribution network capable of the volume of users, bandwidth capacity, comparative reliability and economy of scale to support the existing service levels expected by ISP customers, however spotty service may be at a minority of service addresses.

There remains the question of the cost in a very high cost of living economy like Southern California
of the labor force necessary to sustain, let alone grow, such a complex physical infrastructure,

business data the private ISP corporation is unlikely to make available for public scrutiny or analysis, 

which local officials are regardless unlikely capable of assessing for sake of regulatory administration.

5G may possibly disrupt this paradigm in an atomizing fashion,
putting service administration decisions back on the customer in lieu of now centralized service admin,

but I prefer that ultrahigh frequency signal remain on a wire rather than my body be bombarded by it any & every place I am.

Likely next step is for Cox to load its corporate assets with debt, securitize that debt, then sell the delivery system & service billing base whole or piecemeal at a price that guarantees the buyer(s) will fail financially, sending the entire delivery infrastructure into escalating decline & collapse. The corporate tax write-down for that cascade of losses becomes an additional cost to the taxpayer base that is the customers for the service.

Actual profits from that set of transactions will be booked to offshore accounts to isolate them from taxation, for which process we can thank the magic circle favored by UK financial regulation.  

https://en.wikipedia.org/wiki/Offshore_magic_circle 

I suggest you return to whence you came to resolve the underlying issue.

Because they can.

They also started throttling my fiber optic connection to my VPN at work. And I'm not writing about high data usage. either.

My speeds without VPN are in the 900s. Through my VPN now? 4. Unusable.

Luckily, Century Link has entered my market. Price guarantee for life. 75/mon plus tan for 1 G. 

Bye bye Cox. And to all of you Cox employees, keep your CV updated.

Bro I hope you have safely returned to UK , COX is the definition of Greed I moved to Lake forest in 2021 my bill was 99 buck a month which the service they call gig blast , at the time fastest few month in I got a bill that is higher than 99 buck, i called them they said I used up my data ? I was confused i did not know internet provider give you a data like a cell phone company, apparently 99 bucks will only give you 1 T or 1024 GB of internet usage, so a 4K movie is about 50-100GB modern game is between 65-100 GB I have 3 people in the house that pathetic 1 TB can even last, my sister who live in Irvine was also using COX at the time but luck for her Google Fiber was available, and 75 bucks get you the same speed but unlimited, but I was SOL because COX is still holds LF, not too long after my bill went up again, due to the OG 99 USD bill was " apparently a promotion, now they charge 120 for the same service " a year later I am paying 140 and that will be 170 in 2025. 

P.S there service is so unreliable there is an outage almost every month from mid night to 6 AM, imagine you work day shift and when you get home there is no internet yet they still charge me !

Word to describe COX - despicable, greedy !