What I think may have happened here is that when the house was built the site was cleared of the top soil and when the footing was dug out for the foundations all the sub-soil was spread out over the garden and when the garden was landscaped it was done on the cheap and given only a thin layer of top soil, this happens all too often.
If this is the case, then I think all you can do is to try and improve what you have by adding to the soil to improve drainage and soil structure.
The lawn area can be spiked with a fork using the full depth of the tines at a few inches apart over the entire lawn, otherwise if it is more serious it could be spiked using hollow tines, remove the plugs then brush a sandy top dressing into the holes to improve drainage.
Other areas may be improved by adding plenty of organic matter in the form of well rotted farmyard manure by digging it in to in effect increse the depth of the top soil.
Adding a mulch of leaf mould or wood chips to the surfice will also help.
If it's a heavy clay type soil you have, it can be improved by rough digging in the beds or borders in late autumn and allow the frost action to crumble the clods over the winter.
Good Luck. Tbird+