Last week, Britain’s new government unveiled a plan to make childcare for some families much cheaper: Working parents of kids between the ages of 3 and 4 can soon claim 30 hours of free daycare for 38 weeks each year.

The move, which doubles the current 15-hour allowance, comes as the price of childcare in the country soars. British parents pay an average of £110 (or about $167) to buy 25 hours at “nursery” for a toddler, a roughly 33 percent increase from five years ago.

But some fear further relieving this burden may exacerbate a problem familiar to many American parents: Dwindling access.

Despite Britain’s growing population, the number of its daycare centers hasn’t budged much in the past decade -- and, as demand swells, the length of waiting lists can exceed a typical gestation period. The Economist recently highlighted one new mother's struggle: “Her nine months of maternity leave are about to run out, and despite booking a nursery place soon after becoming pregnant she was too late to beat her chosen nurseries’ two-year waiting lists.”

That’s probably because running a profitable childcare operation anywhere is tough, thanks largely to strict staffing and health regulations, and especially in cities with surging rent costs. Britain’s National Day Nurseries Association estimates 40 percent of its members this year will either break even or suffer a loss.

It doesn't help that the British government underpays centers for the mandated free 15 hours of weekly care, according to the NDNA, and losses add up to an average of £800 (or $1,227) per child annually.

Reimbursement rates in the U.S., meanwhile, are similarly uneven -- and the additional expense falls on families and providers.

About 1.5 million children in the U.S. receive subsidized child-care. And in 2013, only three states set reimbursement rates at the 75th percentile of current market rates, which vary drastically across the country, a report from the National Women’s Law Center found.

Child-care advocates argue this removes incentive for more providers to enter the market.

“I don't know of a state where it’s not a challenge to be a provider who serves subsidized children,” said Christine Johnson-Staub, interim director of childcare and early education at the Center for Law and Social Policy.

Reimbursement rates, set by states and sometimes counties, are generally “quite low," she said. That could change if states make raising them a policy priority under the latest child-care law, which President Obama signed in November.

Today, many daycare centers nationwide don’t accept subsidies. Those open to government vouchers can often accommodate only a sliver of parents seeking spots for their kids. Even rich families have trouble, said Stacy Buchanan, vice president of Qualistar, which tracks daycare costs across Colorado.

Like Britain, the state hasn't seen the number of daycare centers grow in the past decade. "More are closing than opening," Buchanan said.

About 56 percent of daycare centers in Colorado accept subsidies, she said. The number drops to 43 percent for family child-care centers, or those run out of someone’s house.

Though all parents work in 63 percent of Colorado households, the state’s daycare resources can support only a quarter of its kids, according to a 2014 Qualistar report. Full-time center options are available to less than 20 percent of children in 24 counties.

The daycare shortage isn't unique to Colorado. And unless incentives change, access for U.S. families isn't likely to expand any time soon.

“The economics of childcare don't work,” Buchanan said.  "Families can't pay any more. Providers cannot charge any less."