People may just be terrible at assessing percentages. If they mentally round down <10% to "does not happen" then conversely even low fractions will still lead to a reported >10% perception. Maybe the questions should be phrased as X out of 5, i.e. 20% increments. Or even more accurately 0-1 out of 5, 1-2 out of 5, etc.

Also, an anti-immigration stance may just be isolationism, not necessarily racism. Fear of "the other" is more general than just race.