Because the "commoners" haven't organized in UK to take them away and because the "church" and "nobility" control the establishment that makes and enforces laws

Because the "commoners" haven't organized in UK to take them away and because the "church" and "nobility" control the establishment that makes and enforces laws. Establishment derived politicians have largely managed to sway public emotions through appeals to tradition and nostalgia for the empire. In many other parts of the world the property of the nobility was largely taken away - eg. in India a few decades after independence in the 1970s - though the smarter kings managed to retain some control by sensing which way the wind was blowing early and turning into businessmen amd politicians. One strategy used was to endow property to "public" trusts, take controlling board seats and starting businesses contracted by these trusts to extract the income.