Singtel (the most expensive telco) has multiple plans for visitors (100GB for $12 + 500mins talk + 1GB roaming + $3 to spend on public transport). If you want prepaid month to month, it's still nowhere in the stratosphere of $10/GB.
Also 4G coverage is virtually 100%, buildings and Faraday cages aside. (source: living in Singapore for 10 years, through 3G to 4G migration)
This is from Singtel Hi menu:
https://i.imgur.com/z6WmqYx.png
Notice it says "Data plans" - They give you only data and claim to give you free incoming only for 20 days as a bonus. That's not even a bonus, in India, you pay nothing for incoming, at least on the Airtel plan I mentioned.
Also, about your point on being expensive - Singtel is the only Telco that doesn't suck in terms of network coverage in the country. Starhub is a close second, with slightly cheaper plans depending on what you're after and M1 is garbage and everyone knows that.
I suggest you try 4G somewhere near Toa Payoh, Bishan, Bedok or even some places within Paya Lebar.
Not sure why you had to be so rude (5 minutes of research?) and created a new account just to contest this..oh well.
One of the nice things was that each telco would keep changing their plans to be better and better so it paid to pay attention and change plans whenever a better one came along.
I’m with Singtel and don’t have any problems in those places. I even had 4G on Pulau Ubin today. Singtel has a $25/20GB plan for locals, $10/1GB isn’t really representative of typical plans.
My criteria isn't just having 4G, but able to actually use it in decent speeds. This is where Singtel sucks for me - the 4G logo will show on your phone, but pages will never load due to poor connectivity, even with 5 bars. I had this issue across three phones - iPhone, Sony and Samsung.
Singtel ALSO seems to do lot of throttling on videos depending on where in the city you're as well.
As other posts have pointed out, $10/GB is not right (tourist plan or not). If you lived here long enough to know what the rates are, why misrepresent it?