This is a very common mistake most Westerners make. Many Westerners think that way because they generally meet only average working Thai from whom they receive services. To really understand this you should look back in time and It was more obvious in the old time when rich old families or high society people looked down on westerner lifestyles and prohibited their children from associating with westerners. Even now, in well off families and educated expats, they do not think Westerners are any better or richer because they have been to the West and have lived there where poverty, miseries and worst human tragedies exist just the same as in Thailand.