I can't afford that.
You would be best asking Mojang why they charge what they charge, only they can really answer that.
As far as I can tell the cheap Bedrock Realms cost 2/3 of the Java ones, not half, and only allow 2 3 players, you and 2 guests.
The 10 player guest option is more expensive than the Java one.
Ok, I was looking at the subscription rate for the Java Realms, the one time one month fee is twice cost of the small Bedrock Realms and the same as the large Bedrock Realms.
So as far as I can tell the subscription rate for the Java Realms is lower than the cost of the Large Bedrock Realms.
(Though there may be a recurring subscription rate for Bedrock that I haven't found.)
As mentioned, Bedrock has 2 guest version for $4/month and 10 guest version for $8/minth.
Java Realms offers only 10 guest option.
There are 3rd-party solutions such as
https://scalacube.com that offer MC server hosting for as little as $2.50/mo.
Finally, with Java, you can go totally free by downloading and setting up your own server on a home PC, forwarding router port to it and using a Dynamic DNS service such as Duck DNS.