Why is the ten year interest rate lower for Spain/UK bonds than for US?
Inflation forecast is higher in the US than the rest of countries. US here: https://www.statista.com/statistics/244983/projected-inflation-rate-in-the-united-states/ 

Spain here: https://www.statista.com/statistics/271077/inflation-rate-in-spain/

Japan here: https://www.statista.com/statistics/270095/inflation-rate-in-japan/

UK here: https://www.statista.com/statistics/270384/inflation-rate-in-the-united-kingdom/

Because inflation is higher, central banks will raise interest rate higher. Long term rates are higher in consequence.