For CPI-trim, the higher relative importance attached to services could be due to the fact that more goods prices are “trimmed” from the calculation because their movements are sharper and tend to reflect commodity price shocks.
For CPI-common, this could be because prices for services tend to move in tandem since they appear to be largely influenced by labour market conditions and associated wage pressures, given that labour is typically the most important input for the production of many services.