The tariffs are _not_ the same. They can be much cheaper especially if you pick one tailored to your particular usage pattern. Smart meters record your usage in 30 min windows, allowing your provider to charge you in a very granular fashion. If the meter fails to upload the reading data to the cloud, or the cloud fails to pass it on to the supplier, and it cant be retrieved (which is very rare), the supplier will charge you at the non-smart tariff that you were originally sign up with for the days (or sometimes hours) where data is not available.
My neighbours were on the standard Octopus or E-On tariff and moved to the Octopus tracker tariff. It changes price every day based on the prevailing wholesale price of electricity. Much cheaper (in general) than that standard variable tariff. Same for gas.
My latest bill looks like this. Note the average rate per kWh charged...
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