This may well be the case in Katy, Texas today but the assimilation process has broken down in California due to the sheer number of recent immigrants.
For those children of immigrants raised and educated in California during the 1950's through the 1970's your obsevations are substantially true. The spirally numbers of immigrants in the last twenty years in California has interfered with this process. Immigrant children born in California during the 1980's today remain more fluent in their parent's tongue than in English.
They are certainly bilingual but Spanish is the predominant language in the workplace because they deal on a daily basis with the more recent tidal wave of immigrants pouring into California since the 1990s.
Houston Metropolitan Area
The Keys:
1990
Beige 0.0%-11.0% Hispanic
Yellow 11.2%-23.1% Hispanic
Green-Yellow 23.3%-39.3% Hispanic
Olive Green 39.9%-63.4% Hispanic
Forest Green 64.7%-100% Hispanic
2000/2010/2020
Beige 0.0%-14.1% Hispanic
Yellow 14.1%-27.5% Hispanic
Green-Yellow 27.7%-44.5% Hispanic
Olive Green 45.2%-67.1% Hispanic
Forest Green 67.6%-97.2% Hispanic
The Maps:
1990
2000
2010
2020