Google Finance page does NOT allow downloading historical EOD data for certain symbols (especially for indices and international stocks)
For example S&P500 index:
as opposed with this:
(2) has "Download to spreadsheet" link that AmiQuote uses.
(1) does NOT have it.
Without "download to spreadsheet" link on Google Finance AmiQuote can not download EOD data.
Google Intraday is handled by different server / different data supplier and support different set of symbols