I'm not sure BA has thought this through very carefully. As a UA 1K for years, and now a BA Gold, I've seen UA cycle through various iterations of its spend based status and it looks like BA has missed some of the subtleties.

First, UA, and the other Big 3, reward spend on what is profitable for them - essentially credit cards, which are not transparent to the customer. But credit cards are much less profitable in the UK. which is presumably why the Amex offer is so half-hearted and almost irrelevant.
Second, it's clear BA makes a lot of money on BA Holidays with relatively high margins. (Anecdotally, I've always been amazed at how much more it costs to book a BA Holiday than piecing together the separate bits - the delta is just a cheap way of earning more tps). But BA Holidays are quite transparent. It's easy to see how much a hotel should cost.
Third, UA has introduced a full ancillary spend credit for status - buy on board, miles used to buy reward flights etc. etc. BA has done this in a very half-hearted way and is failing to reward spending on BA.
Fourth, UA has recognised the importance of road warriors, so the thresholds are lower for people who do a lot of segments. But BA has chosen to ignore people who do lots of CE shorthaul.

I could go on, but I do believe that this will require quite a lot of tinkering quite quickly.